chore(CI): add GH_TOKEN to dependabot approval

Author: nyurik

.github/workflows/dependabot.yml

@@ -14,6 +14,7 @@ jobs:
         run: gh pr review --approve "$PR_URL"
         env:
           PR_URL: ${{ github.event.pull_request.html_url }}
+          GH_TOKEN: ${{ github.token }}
           GITHUB_TOKEN: ${{ secrets.RELEASE_PLZ_TOKEN }}
       - name: Enable auto-merge for Dependabot PRs
         if: steps.metadata.outputs.update-type == 'version-update:semver-patch'