Update docker.io/postgres Docker tag to v18

.gitea/workflows/render-manifests.yaml

@@ -38,8 +38,10 @@ jobs:
           token: ${{ secrets.GITEA_TOKEN }}
           version: v3.17.2 # Pending https://github.com/helm/helm/pull/30743
 
-      - name: Prepare Manifest Directory
+      - name: Prepare Manifest Branch
         run: |
+          cd ${MANIFEST_DIR}
+
           # Configure Git
           echo ">> Configure git to use gitea-bot as user ..."
           git config user.name "gitea-bot"
@@ -65,6 +67,8 @@ jobs:
 
       - name: Add Repositories
         run: |
+          cd ${MAIN_DIR}
+
           for cluster in ${CLUSTERS}; do
             echo ">> Adding repositories for chart dependencies of cluster $cluster ..."
             for chart_path in ${MAIN_DIR}/clusters/$cluster/helm/*; do
@@ -77,6 +81,8 @@ jobs:
 
       - name: Render Helm Manifests
         run: |
+          cd ${MAIN_DIR}
+
           for cluster in ${CLUSTERS}; do
             for chart_path in ${MAIN_DIR}/clusters/$cluster/helm/*; do
               chart_name=$(basename "$chart_path")