update stubtest (#4696)

Co-authored-by: hauntsaninja <>

.github/workflows/tests.yml

@@ -93,6 +93,6 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install -U pip
-          pip install -U mypy==0.790
+          pip install -U git+git://github.com/python/mypy@af3c8be98f
       - name: Run stubtest
         run: python tests/stubtest_test.py --ignore-unused-whitelist