Remove wrong tests violating the precondition and the assertion (#688)

* Remove wrong tests violating the precondition

The precondition of `RTYPEDDATA_P` is the argument is `RUBY_T_DATA`.

https://github.com/ruby/ruby/blob/ruby_3_1/include/ruby/internal/core/rtypeddata.h#L537
```
 * @pre        `obj` must be a Ruby object of ::RUBY_T_DATA.
```

Must not call with non-data object, such as `Object` or `String`.

* feat: update to Ruby 4.0 release

Author: nobu

.github/workflows/ci.yml

@@ -59,7 +59,7 @@ jobs:
       fail-fast: false
       matrix:
         # Test against all versions supported by rubygems
-        ruby_version: ["2.7", "3.0", "3.1", "3.2", "3.3", "3.4", "4.0.0-preview2"]
+        ruby_version: ["2.7", "3.0", "3.1", "3.2", "3.3", "3.4", "4.0"]
         sys:
           - os: ubuntu-latest
             rust_toolchain: ${{ needs.fetch_ci_data.outputs.minimum-supported-rust-version }}
@@ -108,8 +108,7 @@ jobs:
             sys:
               os: windows-2022
               rust_toolchain: stable
-          # Ruby 4.0 not available on Windows yet
-          - ruby_version: "4.0.0-preview2"
+          - ruby_version: "4.0"
             sys:
               os: windows-2025
               rust_toolchain: stable

crates/rb-sys-tests/src/stable_api_test.rs

@@ -61,10 +61,6 @@ fn gen_non_embedded_typed_data() -> VALUE {
     ruby_eval!("require 'stringio'; StringIO.new('a' * 1000)")
 }
 
-fn gen_non_typed_data() -> VALUE {
-    ruby_eval!("Object.new")
-}
-
 parity_test!(
     name: test_rstring_len_basic,
     func: rstring_len,
@@ -681,24 +677,6 @@ parity_test! (
     expected: true
 );
 
-parity_test! (
-    name: test_rtypeddata_p_for_regular_data,
-    func: rtypeddata_p,
-    data_factory: {
-        gen_non_typed_data()
-    },
-    expected: false
-);
-
-parity_test! (
-    name: test_rtypeddata_p_for_string,
-    func: rtypeddata_p,
-    data_factory: {
-        gen_rstring!("not a typed data")
-    },
-    expected: false
-);
-
 parity_test! (
     name: test_rtypeddata_embedded_p_for_typed_data,
     func: rtypeddata_embedded_p,