Cache for kubernetes tests is updateable (#10945)

The cache in Github Actions is immutable - once you create it
it cannot be modified. That's why cache keys should contain
hash of all files that are used to create the cache.

Kubernetes cache key did not contain it, and as a side effect
the cache from master kubernetes setup.py was used in the v1-10-test
after the breeze changes were cherry-picked.

.github/workflows/ci.yml

@@ -593,7 +593,7 @@ jobs:
           cache-name: cache-kubernetes-tests-virtualenv-v3
         with:
           path: .build/.kubernetes_venv
-          key: "${{ env.cache-name }}-${{ github.job }}-v1"
+          key: "${{ env.cache-name }}-${{ github.job }}-${{ hashFiles('setup.py') }}-v1"
       - name: "Kubernetes Tests"
         run: ./scripts/ci/kubernetes/ci_run_kubernetes_tests.sh
       - name: "Upload KinD logs"