[ci] Avoid stopping the build if the QA checks fail

.github/workflows/ci.yml

@@ -48,6 +48,7 @@ jobs:
         run: ansible-galaxy collection install "community.general:>=3.6.0"
 
       - name: QA checks
+        continue-on-error: true
         run: |
           openwisp-qa-check --skip-isort --skip-flake8 --skip-checkmigrations --skip-black