pin to tox<4

Author: mr-c

.github/workflows/ci-tests.yml

@@ -57,7 +57,7 @@ jobs:
       - name: Upgrade setuptools and install tox
         run: |
           pip install -U pip setuptools wheel
-          pip install tox tox-gh-actions
+          pip install 'tox<4' tox-gh-actions
 
       - name: MyPy cache
         if: ${{ matrix.step == 'mypy' }}
@@ -108,7 +108,7 @@ jobs:
       - name: Upgrade setuptools and install tox
         run: |
           pip install -U pip setuptools wheel
-          pip install tox tox-gh-actions
+          pip install 'tox<4' tox-gh-actions
 
       - if: ${{ matrix.step == 'pydocstyle' && github.event_name == 'pull_request'}}
         name: Create local branch for diff-quality for PRs