ci: update helm release to use vault

Author: yorugac

.github/workflows/helm-release.yaml

@@ -1,6 +1,9 @@
 
 name: Helm release
-permissions: {}
+# These permissions are needed to assume roles from Github's OIDC.
+permissions:
+  contents: read
+  id-token: write
 
 on:
   workflow_dispatch: {}
@@ -61,11 +64,14 @@ jobs:
     needs:
       - generate-chart-schema
     uses: grafana/helm-charts/.github/workflows/update-helm-repo.yaml@main
+    permissions:
+      id-token: write
+      contents: write
+      packages: write
     with:
       charts_dir: charts
       cr_configfile: charts/cr.yaml
       ct_configfile: charts/ct.yaml
       helm_tag_prefix: helm
     secrets:
-      github_app_id: ${{ secrets.K6_OPERATOR_HELM_RELEASE_APP_ID }}
-      github_app_pem: ${{ secrets.K6_OPERATOR_HELM_RELEASE_PEM_KEY }}
+      vault_repo_secret_name: github-app