use github token (#107)

Author: alan707

.github/workflows/dependabot-automerge.yml

@@ -26,7 +26,7 @@ jobs:
         id: meta
         uses: dependabot/fetch-metadata@v2
         with:
-          github-token: ${{ secrets.GH_AUTOMERGE_PAT }}
+          github-token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Check if upstream submodule
         id: check