Fix mypy pre-commit problems

The command `pre-comment run -a` doesn't do all the things that Pandas CI/CD does.  This commit fixes two problems found in the mypy section:

* Adding some comments to ignore some errors in _ensure_data for complex dtypes
* Fix the type signature of _get_expected_exception to match LSP stylings

Signed-off-by: Michael Tiemann <72577720+MichaelTiemannOSC@users.noreply.github.com>

Author: MichaelTiemannOSC

pandas/core/algorithms.py

@@ -167,7 +167,9 @@ def _ensure_data(values: ArrayLike) -> np.ndarray:
         return np.asarray(values)
 
     elif is_complex_dtype(values.dtype):
-        if values.dtype.itemsize == 16:
+        # error: Item "ExtensionDtype" of "Union[Any, ExtensionDtype]"
+        # has no attribute "itemsize"
+        if values.dtype.itemsize == 16:  # type: ignore[union-attr]
             # We have support for complex128
             return np.asarray(values)
         return cast(np.ndarray, values)

pandas/tests/extension/decimal/test_decimal.py

@@ -330,7 +330,7 @@ class TestArithmeticOps(base.BaseArithmeticOpsTests):
     series_array_exc = None
 
     def _get_expected_exception(
-        self, op_name: str, obj, other
+        self, op_name: str, obj, other, *args, **kwargs
     ) -> type[Exception] | None:
         return None