Move minimum version up to 3.9

Author: andrewgodwin

README.rst

@@ -96,7 +96,7 @@ file handles for incoming POST bodies).
 Dependencies
 ------------
 
-``asgiref`` requires Python 3.8 or higher.
+``asgiref`` requires Python 3.9 or higher.
 
 
 Contributing

setup.cfg

@@ -16,7 +16,6 @@ classifiers =
     Programming Language :: Python
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
@@ -29,7 +28,7 @@ project_urls =
     Changelog = https://github.com/django/asgiref/blob/master/CHANGELOG.txt
 
 [options]
-python_requires = >=3.8
+python_requires = >=3.9
 packages = find:
 include_package_data = true
 install_requires =