Use 3.8 to run flake8

.github/workflows/lint.yml

@@ -8,10 +8,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
-    - name: Set up Python 3.7
+    - name: Set up Python 3.8
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.8
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip

tox.ini

@@ -45,13 +45,13 @@ deps =
 commands = {posargs:py.test --cov=graphene_django graphene_django examples}
 
 [testenv:black]
-basepython = python3.7
+basepython = python3.8
 deps = -e.[dev]
 commands  =
     black --exclude "/migrations/" graphene_django examples setup.py --check
 
 [testenv:flake8]
-basepython = python3.7
+basepython = python3.8
 deps = -e.[dev]
 commands =
-    flake8 graphene_django examples
+    flake8 graphene_django examples setup.py