ci: Fix testing dependencies (#936)

Author: DenverCoder1

.github/workflows/test.yml

@@ -33,7 +33,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip setuptools wheel
-        python -m pip install tox tox-gh-actions==2.1.0
+        python -m pip install 'tox<4.0.0' 'tox-gh-actions==2.12.0'
     - name: Run test via Tox
       run: tox --skip-missing-interpreters
       env: