Remove mypy_test_suite (#5543)

Closes: #5540

.github/workflows/tests.yml

@@ -72,15 +72,6 @@ jobs:
       - run: pip install -U git+git://github.com/python/mypy
       - run: ./tests/mypy_test.py --platform=${{ matrix.platform }}
 
-  mypy-test-suite:
-    name: Run the mypy test suite
-    # Ubuntu 20.04 doesn't have the Python 2 venv module.
-    runs-on: ubuntu-18.04
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
-      - run: ./tests/mypy_test_suite.py
-
   pyright:
     name: Run pyright against the stubs
     runs-on: ubuntu-latest