upgrade: update dependency dart to v3.2.0 (#452)

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This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [dart](https://dart.dev/)
([source](https://togithub.com/dart-lang/sdk)) | minor | `3.1.5` ->
`3.2.0` |

---

### Release Notes

<details>
<summary>dart-lang/sdk (dart)</summary>

###
[`v3.2.0`](https://togithub.com/dart-lang/sdk/blob/HEAD/CHANGELOG.md#320)

[Compare
Source](https://togithub.com/dart-lang/sdk/compare/3.1.5...3.2.0)

##### Language

Dart 3.2 adds the following features. To use them, set your package's
[SDK
constraint][language version] lower bound to 3.2 or greater (`sdk:
'^3.2.0'`).

[language version]: https://dart.dev/guides/language/evolution

- **Private field promotion**: In most circumstances, the types of
private final
fields can now be promoted by null checks and `is` tests. For example:

    ```dart
    class Example {
      final int? _privateField;
      Example(this._privateField);

      f() {
        if (_privateField != null) {
          // _privateField has now been promoted; you can use it without
          // null checking it.
          int i = _privateField; // OK
        }
      }
    }

    // Private field promotions also work from outside of the class:
    f(Example x) {
      if (x._privateField != null) {
        int i = x._privateField; // OK
      }
    }
    ```

To ensure soundness, a field is not eligible for field promotion in the
    following circumstances:

- If it's not final (because a non-final field could be changed in
between the
        test and the usage, invalidating the promotion).
- If it's overridden elsewhere in the library by a concrete getter or a
non-final field (because an access to an overridden field might resolve
at
        runtime to the overriding getter or field).
- If it's not private (because a non-private field might be overridden
        elsewhere in the program).
- If it has the same name as a concrete getter or a non-final field in
some
other unrelated class in the library (because a class elsewhere in the
program might extend one of the classes and implement the other,
creating an
        override relationship between them).
- If there is a concrete class `C` in the library whose interface
contains a
getter with the same name, but `C` does not have an implementation of
that
getter (such unimplemented getters aren't safe for field promotion,
because
they are implicitly forwarded to `noSuchMethod`, which might not return
the
        same value each time it's called).

- **Breaking Change** [#&#8203;53167][]: Use a more precise split point
for refutable
patterns. Previously, in an if-case statement, if flow analysis could
prove
that the scrutinee expression was guaranteed to throw an exception, it
would
sometimes fail to propagate type promotions implied by the pattern to
the
(dead) code that follows. This change makes the type promotion behavior
of
if-case statements consistent regardless of whether the scrutinee
expression
    throws an exception.

No live code is affected by this change, but there is a small chance
that the
change in types will cause a compile-time error to appear in some dead
code in
    the user's project, where no compile-time error appeared previously.

[#&#8203;53167]: https://togithub.com/dart-lang/sdk/issues/53167

##### Libraries

##### `dart:async`

-   Added `broadcast` parameter to `Stream.empty` constructor.

##### `dart:convert`

-   **Breaking change** [#&#8203;52801][]:
- Changed return types of `utf8.encode()` and `Utf8Codec.encode()` from
        `List<int>` to `Uint8List`.

[#&#8203;52801]: https://togithub.com/dart-lang/sdk/issues/52801

##### `dart:developer`

-   Deprecated the `Service.getIsolateID` method.
-   Added `getIsolateId` method to `Service`.
-   Added `getObjectId` method to `Service`.

##### `dart:ffi`

-   Added the `NativeCallable.isolateLocal` constructor. This creates
`NativeCallable`s with the same functionality as `Pointer.fromFunction`,
    except that `NativeCallable` accepts closures.
- Added the `NativeCallable.keepIsolateAlive` method, which determines
whether
    the `NativeCallable` keeps the isolate that created it alive.
- All `NativeCallable` constructors can now accept closures. Previously
`NativeCallable`s had the same restrictions as `Pointer.fromFunction`,
and
    could only create callbacks for static functions.
- **Breaking change**
\[[#&#8203;53311](https://togithub.com/dart-lang/sdk/issues/53311)]\[]:
`NativeCallable.nativeFunction` now throws an
error if is called after the `NativeCallable` has already been `close`d.
Calls
    to `close` after the first are now ignored.

##### `dart:io`

-   **Breaking change** [#&#8203;53005][]: The headers returned by
`HttpClientResponse.headers` and `HttpRequest.headers` no longer include
    trailing whitespace in their values.

- **Breaking change** [#&#8203;53227][]: Folded headers values returned
by
`HttpClientResponse.headers` and `HttpRequest.headers` now have a space
    inserted at the fold point.

[#&#8203;53005]: https://dartbug.com/53005

[#&#8203;53227]: https://dartbug.com/53227

##### `dart:isolate`

- Added `Isolate.packageConfigSync` and `Isolate.resolvePackageUriSync`
APIs.

##### `dart:js_interop`

-   **Breaking Change on JSNumber.toDart and Object.toJS**:
`JSNumber.toDart` is removed in favor of `toDartDouble` and `toDartInt`
to
    make the type explicit. `Object.toJS` is also removed in favor of
`Object.toJSBox`. Previously, this function would allow Dart objects to
flow
into JS unwrapped on the JS backends. Now, there's an explicit wrapper
that is
    added and unwrapped via `JSBoxedDartObject.toDart`. Similarly,
`JSExportedDartObject` is renamed to `JSBoxedDartObject` and the
extensions
`ObjectToJSExportedDartObject` and `JSExportedDartObjectToObject` are
renamed
to `ObjectToJSBoxedDartObject` and `JSBoxedDartObjectToObject` in order
to
    avoid confusion with `@JSExport`.
-   **Type parameters in external APIs**:
Type parameters must now be bound to a static interop type or one of the
`dart:js_interop` types like `JSNumber` when used in an external API.
This
only affects `dart:js_interop` classes and not `package:js` or other
forms of
    JS interop.
-   **Subtyping `dart:js_interop` types**:
`@staticInterop` types can subtype only `JSObject` and `JSAny` from the
set of
JS types in `dart:js_interop`. Subtyping other types from
`dart:js_interop`
would result in confusing type errors before, so this makes it a static
error.
-   **Global context of `dart:js_interop` and `@staticInterop` APIs**:
Static interop APIs will now use the same global context as non-static
interop
instead of `globalThis` to avoid a greater migration. Static interop
APIs,
either through `dart:js_interop` or the `@staticInterop` annotation,
have used
JavaScript's `globalThis` as the global context. This is relevant to
things
like external top-level members or external constructors, as this is the
root
context we expect those members to reside in. Historically, this was not
the
case in Dart2JS and DDC. We used either `self` or DDC's `global` in
non-static
interop APIs with `package:js`. So, static interop APIs will now use one
of
those global contexts. Functionally, this should matter in only a very
small
number of cases, like when using older browser versions.
`dart:js_interop`'s
`globalJSObject` is also renamed to `globalContext` and returns the
global
    context used in the lowerings.
-   **Breaking Change on Types of `dart:js_interop` External APIs**:
External JS interop APIs when using `dart:js_interop` are restricted to
a set
of allowed types. Namely, this include the primitive types like
`String`, JS
types from `dart:js_interop`, and other static interop types (either
through
    `@staticInterop` or extension types).
-   **Breaking Change on `dart:js_interop` `isNull` and `isUndefined`**:
`null` and `undefined` can only be discerned in the JS backends.
dart2wasm
conflates the two values and treats them both as Dart null. Therefore,
these
two helper methods should not be used on dart2wasm and will throw to
avoid
    potentially erroneous code.
- **Breaking Change on `dart:js_interop` `typeofEquals` and
`instanceof`**:
Both APIs now return a `bool` instead of a `JSBoolean`. `typeofEquals`
also
    now takes in a `String` instead of a `JSString`.
-   **Breaking Change on `dart:js_interop` `JSAny` and `JSObject`**:
    These types can only be implemented, and no longer extended, by user
    `@staticInterop` types.
-   **Breaking Change on `dart:js_interop` `JSArray.withLength`**:
    This API now takes in an `int` instead of `JSNumber`.

##### Tools

##### Development JavaScript compiler (DDC)

- Applications compiled by DDC will no longer add members to the native
    JavaScript Object prototype.
-   **Breaking change for JS interop with Symbols and BigInts**:
    JavaScript `Symbol`s and `BigInt`s are now associated with their own
interceptor and should not be used with `package:js` classes. These
types were
being intercepted with the assumption that they are a subtype of
JavaScript's
`Object`, but this is incorrect. This lead to erroneous behavior when
using
these types as Dart `Object`s. See [#&#8203;53106][] for more details.
Use
`dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to
interop
    with these types.

##### Production JavaScript compiler (dart2js)

-   **Breaking change for JS interop with Symbols and BigInts**:
    JavaScript `Symbol`s and `BigInt`s are now associated with their own
interceptor and should not be used with `package:js` classes. These
types were
being intercepted with the assumption that they are a subtype of
JavaScript's
`Object`, but this is incorrect. This lead to erroneous behavior when
using
these types as Dart `Object`s. See [#&#8203;53106][] for more details.
Use
`dart:js_interop`'s `JSSymbol` and `JSBigInt` with extension types to
interop
    with these types.

[#&#8203;53106]: https://togithub.com/dart-lang/sdk/issues/53106

##### Dart command line

-   The `dart create` command has a new `cli` template
    to quickly create Dart command-line applications
    with basic argument parsing capabilities.
    To learn more about using the template,
    run `dart help create`.

##### Dart format

-   Always split enum declarations containing a line comment.
-   Fix regression in splitting type annotations with library prefixes.
-   Support `--enable-experiment` command-line option to enable language
    experiments.

##### DevTools

- Incorporated the [2.26.1][devtools-2-26-1], [2.27.0][devtools-2-27-0],
and
    [2.28.1][devtools-2-28-1] releases of DevTools.

[devtools-2-26-1]:
https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.26.1

[devtools-2-27-0]:
https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.27.0

[devtools-2-28-1]:
https://docs.flutter.dev/tools/devtools/release-notes/release-notes-2.28.1

##### Linter

- Added the experimental [`annotate_redeclares`][annotate_redeclares]
lint.
- Marked the
[`use_build_context_synchronously`][use_build_context_synchronously]
lint as stable.

[`annotate_redeclares`]: https://dart.dev/lints/annotate_redeclares

[`use_build_context_synchronously`]:
https://dart.dev/lints/use_build_context_synchronously

##### Pub

- New option `dart pub upgrade --tighten` which will update
dependencies' lower
    bounds in pubspec.yaml to match the current version.
- The commands `dart pub get`/`add`/`upgrade` will now show if a
dependency
    changed between direct, dev and transitive dependency.
- The command `dart pub upgrade` no longer shows unchanged dependencies.

</details>

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.tool-versions

@@ -1,2 +1,2 @@
-dart 3.1.5
+dart 3.2.0
 flutter 3.13.9-stable