STYLE: Remove unused typing imports after pyupgrade modernization

Remove Union and Optional imports that are no longer referenced after
pyupgrade converted type annotations to PEP 604 syntax (X | Y).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hjmjohnson

Wrapping/Generators/Python/itk/pyi_generator.py

@@ -10,7 +10,6 @@
 from io import StringIO
 from pathlib import Path, PurePath
 import pickle
-from typing import Union
 import glob
 import re
 from collections import defaultdict

Wrapping/Generators/Python/itk/support/base.py

@@ -21,7 +21,7 @@
 from sys import stderr as system_error_stream
 
 # Required to work around weird import error with xarray
-from typing import Any, Optional, Union
+from typing import Any
 from collections.abc import Sequence
 
 import itkConfig

Wrapping/Generators/Python/itk/support/init_helpers.py

@@ -1,6 +1,5 @@
 from sys import stderr as _system_error_stream
 from enum import IntEnum, unique
-from typing import Union
 
 __all__ = [
     "auto_not_in_place",

Wrapping/Generators/Python/itk/support/template_class.py

@@ -23,7 +23,7 @@
 import types
 import collections
 import warnings
-from typing import Any, Union
+from typing import Any
 from collections.abc import Callable
 
 import itkConfig