chore(deps): update docker/metadata-action action to v6

Author: renovate[bot]

.github/workflows/main.yml

@@ -62,7 +62,7 @@ jobs:
 
       - name: Docker meta
         id: docker_action_meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ghcr.io/splunk/wfe-test-runner-action/wfe-test-runner-action
           tags: |