Remove tox cache in gh-actions to prevent no space error

Error message:

    ERROR: Could not install packages due to an OSError: [Errno 28] No space left on device

.github/workflows/test-with-tox.yaml

@@ -33,6 +33,8 @@ jobs:
         pip install tox tox-gh-actions
     - name: Test with tox
       run: tox
+    - name: Remove tox cache
+      run: rm -rf .tox
     - name: Prepare code coverage data
       if: matrix.platform == 'ubuntu-22.04' && matrix.python-version == 3.9
       run: |