Update helm/chart-testing-action action to v2.7.0 (#271)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -274,7 +274,7 @@ jobs:
           name: chart
           path: chart/
       - name: Set up chart-testing
-        uses: helm/chart-testing-action@v2.6.1
+        uses: helm/chart-testing-action@v2.7.0
       - name: Install
         run: ct install --charts chart/ --namespace test
   helm-upgrade: