Remove version filter in tox file.

Author: taeold

tox.ini

@@ -30,8 +30,7 @@ deps =
     pytest-integration
     pretend
 extras =
-    # Only include async extra for Python 3.8+
-    py{38,39,310,311,312}: async
+    async
 setenv =
     PYTESTARGS = --cov=functions_framework --cov-branch --cov-report term-missing --cov-fail-under=100
     windows-latest: PYTESTARGS =