chore: enable 'warn_redundant_casts' for mypy

Enable 'warn_redundant_casts'for mypy and resolve one issue.

gitlab/v4/objects/keys.py

@@ -31,4 +31,4 @@ def get(
         server_data = self.gitlab.http_get(self.path, **kwargs)
         if TYPE_CHECKING:
             assert isinstance(server_data, dict)
-        return cast(Key, self._obj_cls(self, server_data))
+        return self._obj_cls(self, server_data)

pyproject.toml

@@ -12,6 +12,7 @@ disallow_incomplete_defs = true
 disallow_subclassing_any = true
 disallow_untyped_decorators = true
 disallow_untyped_defs = true
+warn_redundant_casts = true
 warn_unused_configs = true
 warn_unused_ignores = true
 
@@ -21,7 +22,6 @@ warn_unused_ignores = true
 # no_implicit_optional = true
 # no_implicit_reexport = true
 # strict_equality = true
-# warn_redundant_casts = true
 # warn_return_any = true
 
 [[tool.mypy.overrides]] # Overrides for currently untyped modules