Pin typing_extensions high enough for our use of it

Author: andrewgodwin

setup.cfg

@@ -32,7 +32,7 @@ python_requires = >=3.7
 packages = find:
 include_package_data = true
 install_requires =
-    typing_extensions; python_version < "3.11"
+    typing_extensions>=4; python_version < "3.11"
 zip_safe = false
 
 [options.extras_require]