[ci] CI maintenance

- Updated Python versions
- Always update pip to the latest available version
- Avoid stopping build if QA checs fail

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.7, 3.8, 3.9]
+        python-version: [3.8, 3.9, 3.10]
 
     steps:
     - uses: actions/checkout@v2
@@ -28,13 +28,15 @@ jobs:
         python-version: ${{ matrix.python-version }}
 
     - name: Install dependencies
+      id: deps
       run: |
-        pip install -U "pip==20.2.4" wheel setuptools
+        pip install -U pip wheel setuptools
         pip install tox tox-gh-actions
         pip install openwisp-utils[qa]@https://github.com/openwisp/openwisp-utils/tarball/master
 
     - name: QA checks
       run: ./run-qa-checks
 
     - name: Test
+      if: ${{ !cancelled() && steps.deps.conclusion == 'success' }}
       run: tox