Workaround for actions/setup-python#866

Author: nealian

.github/workflows/tests.yml

@@ -19,6 +19,8 @@ jobs:
       uses: LizardByte/setup-python-action@master
       with:
         python-version: ${{ matrix.python-version }}
+      env:
+        PIP_TRUSTED_HOST: "pypi.python.org pypi.org files.pythonhosted.org"
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip wheel