Update Helm release postgres-cluster to v6

.gitea/workflows/lint-test.yaml

@@ -32,7 +32,7 @@ jobs:
         run: |
           set -e  # Exit immediately if a command exits with a non-zero status.
 
-          TARGET_BRANCH="${{ gitea.head_ref }}/${{ gitea.base_ref }}"
+          TARGET_BRANCH="origin/${{ gitea.base_ref }}"
           echo "Target branch for diff is: $TARGET_BRANCH"
 
           CHANGED_FILES=$(git diff --name-only "$TARGET_BRANCH" -- 'clusters/**')