Drop Python 3.9 support (#673)

It reached EOL on 2025-10-31: https://peps.python.org/pep-0596/#lifespan.

Author: adamchainz

.github/ISSUE_TEMPLATE/issue.yml

@@ -6,7 +6,7 @@ body:
   attributes:
     label: Python Version
     description: Which version of Python were you using?
-    placeholder: 3.9.0
+    placeholder: 3.14.0
   validations:
     required: false
 - type: input

.github/workflows/main.yml

@@ -21,7 +21,6 @@ jobs:
         - ubuntu-24.04
         - windows-2022
         python-version:
-        - '3.9'
         - '3.10'
         - '3.11'
         - '3.12'

docs/changelog.rst

@@ -2,6 +2,8 @@
 Changelog
 =========
 
+* Drop Python 3.9 support.
+
 6.11.0 (2025-09-18)
 -------------------
 

pyproject.toml

@@ -21,7 +21,7 @@ maintainers = [
 authors = [
   { name = "David Evans" },
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 classifiers = [
   "Development Status :: 5 - Production/Stable",
   "Framework :: Django",
@@ -33,7 +33,6 @@ classifiers = [
   "Intended Audience :: Developers",
   "Operating System :: OS Independent",
   "Programming Language :: Python :: 3 :: Only",
-  "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",

src/whitenoise/base.py

@@ -3,8 +3,8 @@
 import os
 import re
 import warnings
+from collections.abc import Callable
 from posixpath import normpath
-from typing import Callable
 from wsgiref.headers import Headers
 from wsgiref.util import FileWrapper
 

src/whitenoise/storage.py

@@ -6,7 +6,7 @@
 import textwrap
 from collections.abc import Generator, Iterator
 from concurrent.futures import ThreadPoolExecutor, as_completed
-from typing import Any, Union
+from typing import Any
 
 from django.conf import settings
 from django.contrib.staticfiles.storage import (
@@ -16,7 +16,7 @@
 
 from whitenoise.compress import Compressor
 
-_PostProcessT = Iterator[Union[tuple[str, str, bool], tuple[str, None, RuntimeError]]]
+_PostProcessT = Iterator[tuple[str, str, bool] | tuple[str, None, RuntimeError]]
 
 
 class CompressedStaticFilesStorage(StaticFilesStorage):

tox.ini

@@ -8,7 +8,6 @@ env_list =
     py312-django{60, 52, 51, 50, 42}
     py311-django{52, 51, 50, 42}
     py310-django{52, 51, 50, 42}
-    py39-django{42}
 
 [testenv]
 runner = uv-venv-lock-runner