Run format and mypy on Python 3.8

Author: Kludex

tox.ini

@@ -3,10 +3,10 @@ envlist = format, py{38, 39, 310, 311, 312, py3}, mypy
 
 [gh-actions]
 python =
-    3.8: py38
+    3.8: py38, format, mypy
     3.9: py39
     3.10: py310
-    3.11: py311, format, mypy
+    3.11: py311
     3.12: py312
     pypy-3.9: pypy3
     pypy-3.10: pypy3
@@ -16,7 +16,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = pytest --cov=h11 --cov-config=.coveragerc h11
 
 [testenv:format]
-basepython = python3.10
+basepython = python3.8
 deps = -r{toxinidir}/format-requirements.txt
 commands =
     black --check --diff h11/ bench/ examples/ fuzz/