DPE-781 Run integration tests for passed lint/unit tests only (#38)

Avoid a long-running integration test in case of failing gatekeeping tests.
It will slightly increase the complete tests scope runtime
but will save (a lot?) of electricity/money for Canonical as often
new pull requests have some initial typos/issues to be polished.

.github/workflows/ci.yaml

@@ -13,6 +13,7 @@ jobs:
         run: python3 -m pip install tox
       - name: Run linters
         run: tox -e lint
+
   unit-test:
     name: Unit tests
     runs-on: ubuntu-latest
@@ -23,8 +24,12 @@ jobs:
         run: python -m pip install tox
       - name: Run tests
         run: tox -e unit
+
   integration-test-microk8s:
     name: Integration tests (microk8s)
+    needs:
+      - lint
+      - unit-test
     runs-on: ubuntu-latest
     steps:
       - name: Checkout