Update Helm release postgres-cluster to v6

.gitea/workflows/lint-test.yaml

@@ -1,37 +0,0 @@
-name: lint-and-test-charts
-
-on: pull_request
-
-jobs:
-  lint-test:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Set up Helm
-        uses: azure/setup-helm@v4
-        with:
-          version: latest
-
-      - uses: actions/setup-python@v5
-        with:
-          python-version: "3.13"
-          check-latest: true
-
-      - name: Set up chart-testing
-        uses: helm/chart-testing-action@v2.7.0
-
-      - name: Run chart-testing (list-changed)
-        id: list-changed
-        run: |
-          changed=$(ct list-changed --target-branch ${{ github.event.repository.default_branch }})
-          if [[ -n "$changed" ]]; then
-            echo "changed=true" >> "$GITHUB_OUTPUT"
-          fi
-
-      - name: Run chart-testing (lint)
-        if: steps.list-changed.outputs.changed == 'true'
-        run: ct lint --target-branch ${{ github.event.repository.default_branch }}