Fix typing import in Python utils.py

Author: karthiknadig

generator/plugins/python/utils.py

@@ -164,7 +164,7 @@ def _reset(self):
         self._imports: List[str] = [
             "import enum",
             "import functools",
-            "from typing import Any, Dict, List, Optional, Tuple, TypeAlias, Union",
+            "from typing import Any, Dict, List, Optional, Tuple, Union",
             "import attrs",
             "from . import validators",
         ]
@@ -576,7 +576,8 @@ def _add_type_alias(self, type_alias: model.TypeAlias) -> None:
         if type_alias.type.kind == "reference" and not self._has_type(
             type_alias.type.name
         ):
-            type_name = f"TypeAlias[{type_name}]"
+            # TODO: remove workaround for lack of TypeAlias
+            type_name = f"Union[{type_name}, {type_name}]"
 
         if type_name:
             # clean up the docstring for the class itself.
@@ -587,7 +588,7 @@ def _add_type_alias(self, type_alias: model.TypeAlias) -> None:
                 f"# Since: {_sanitize_comment(type_alias.since)}"
                 if type_alias.since
                 else "",
-                f"# Proposed" if type_alias.proposed else "",
+                "# Proposed" if type_alias.proposed else "",
             ]
         else:
             doc = _get_indented_documentation(type_alias.documentation, indent)