MAINT: adjust typing annotations to pyproject-metadata 0.8.0

mypy is always run with the latest version of the dependencies.

mesonpy/__init__.py

@@ -248,7 +248,7 @@ def _validate_name(name: str) -> str:
         return name
 
     @classmethod
-    def from_pyproject(cls, data: Mapping[str, Any], project_dir: Path) -> Metadata:  # type: ignore[override]
+    def from_pyproject(cls, data: Mapping[str, Any], project_dir: Path) -> Self:
         # The class method from the pyproject_metadata base class is not
         # typed in a subclassing friendly way, thus annotations to ignore
         # typing are needed.
@@ -266,7 +266,7 @@ def from_pyproject(cls, data: Mapping[str, Any], project_dir: Path) -> Metadata:
             fields = ', '.join(f'"{x}"' for x in unsupported_dynamic)
             raise pyproject_metadata.ConfigurationError(f'Unsupported dynamic fields: {fields}')
 
-        return metadata  # type: ignore[return-value]
+        return metadata
 
     # Local fix for a bug in pyproject-metadata. See
     # https://github.com/mesonbuild/meson-python/issues/454