Update helm/chart-testing-action action to v2.8.0 (#2468)

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

Author: renovate[bot]

.github/workflows/test-helm-charts.yml

@@ -26,7 +26,7 @@ jobs:
           python-version: 3.13
 
       - name: Set up chart-testing
-        uses: helm/chart-testing-action@0d28d3144d3a25ea2cc349d6e59901c4ff469b3b # v2.7.0
+        uses: helm/chart-testing-action@6ec842c01de15ebb84c8627d2744a0c2f2755c9f # v2.8.0
 
       - name: Run chart-testing (lint)
         run: ct lint --config ct.yaml