Update chart-testing-action to version 2.8.0

Author: pierluigilenoci

.github/workflows/lint-test.yaml

@@ -20,7 +20,7 @@ jobs:
           check-latest: true
 
       - name: Set up chart-testing
-        uses: helm/chart-testing-action@v2
+        uses: helm/chart-testing-action@v2.8.0
 
       - name: Run chart-testing (list-changed)
         id: list-changed