fix: Handle image version updates gracefully when no changes detected

Changed the 'Update values.yaml' step to skip error exit when no version updates
are available. Instead of failing with exit 1, the workflow now logs an INFO
message and continues execution, allowing the workflow to complete successfully
when versions are already up to date.

- Changed ERROR message to INFO message
- Replaced exit 1 with conditional logic
- Added else clause to log when changes are detected

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.gitea/workflows/image-update-and-release.yaml

@@ -195,9 +195,10 @@ jobs:
           
           # 実際に変更されたか確認
           if diff -q values.yaml.bak values.yaml > /dev/null; then
-            echo "ERROR: No changes were made to values.yaml"
+            echo "INFO: No changes were made to values.yaml (versions already up to date)"
             cat values.yaml | grep -A 5 "image:"
-            exit 1
+          else
+            echo "Changes detected in values.yaml"
           fi
           
           echo "=== Updated values.yaml (image section) ==="