Update tox.ini

Author: aryaniyaps

tox.ini

@@ -11,7 +11,7 @@ commands =
     py{36,37,38}: pytest --cov=graphene graphene examples {posargs}
 
 [testenv:pre-commit]
-basepython=python3.7
+basepython=python3.8
 deps =
     pre-commit>=2,<3
 setenv =
@@ -20,16 +20,16 @@ commands =
     pre-commit {posargs:run --all-files}
 
 [testenv:mypy]
-basepython=python3.7
+basepython=python3.8
 deps =
     mypy>=0.761,<1
 commands =
     mypy graphene
 
 [testenv:flake8]
-basepython=python3.7
+basepython=python3.8
 deps =
-    flake8>=3.7,<4
+    flake8>=3.8,<4
 commands =
     pip install --pre -e .
     flake8 graphene