Bump MSRV to 1.85

```
  error: failed to parse manifest at `/home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/toml_datetime-1.1.0+spec-1.1.0/Cargo.toml`

  Caused by:
    feature `edition2024` is required

    The package requires the Cargo feature called `edition2024`, but that feature is not stabilized in this version of Cargo (1.82.0 (8f40fc59f 2024-08-21)).
    Consider trying a newer version of Cargo (this may require the nightly release).
    See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#edition-2024 for more information about the status of this feature.
```

Author: taiki-e

Cargo.toml

@@ -3,7 +3,7 @@ name = "cargo-hack"
 version = "0.6.44" #publish:version
 edition = "2021"
 # NB: Sync with the MSRV in "From source" section in README.md.
-rust-version = "1.82" # For indexmap
+rust-version = "1.85" # For toml_edit
 license = "Apache-2.0 OR MIT"
 repository = "https://github.com/taiki-e/cargo-hack"
 keywords = ["cargo", "subcommand", "testing"]

README.md

@@ -469,7 +469,7 @@ fields of [`cargo metadata`][cargo-metadata].*
 cargo +stable install cargo-hack --locked
 ```
 
-Currently, installing cargo-hack requires rustc 1.82+.
+Currently, installing cargo-hack requires rustc 1.85+.
 
 cargo-hack is usually runnable with Cargo versions older than the Rust version
 required for installation (e.g., `cargo +1.31 hack check`). Currently, to run