Re-drop dependency on typing_extensions (#269)

Since it was only being used for `TypedDict`, which was added in
Python 3.8 and `dj-database-url` v2.3.0+ only supports Python 3.9+.

See:
https://docs.python.org/3.12/library/typing.html#typing.TypedDict
https://github.com/jazzband/dj-database-url/blob/master/CHANGELOG.md#v230-2024-10-23

Note: This is a repeat of #257, since that PR was lost as part
of merges that occurred during the release of 3.0.0:
https://github.com/jazzband/dj-database-url/pull/257#issuecomment-3023857093

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## Unreleased
+
+* Drop dependency on `typing_extensions`.
+
 ## v3.0.0 (2025-05-18)
 > Bumping to version 3; changes to code do break some API compatability.
 * Implement a new decorator registry pattern to impement checks on database connection string.

dj_database_url/__init__.py

@@ -1,9 +1,7 @@
 import logging
 import os
 import urllib.parse as urlparse
-from typing import Any, Callable, Dict, List, Optional, Union
-
-from typing_extensions import TypedDict
+from typing import Any, Callable, Dict, List, Optional, TypedDict, Union
 
 DEFAULT_ENV = "DATABASE_URL"
 ENGINE_SCHEMES: Dict[str, "Engine"] = {}

setup.py

@@ -14,7 +14,7 @@ setup(
     long_description=readme,
     long_description_content_type="text/x-rst",
     packages=["dj_database_url"],
-    install_requires=["Django>=4.2", "typing_extensions>=4.0.0"],
+    install_requires=["Django>=4.2"],
     include_package_data=True,
     package_data={
         "dj_database_url": ["py.typed"],