chore: update dependabot merge action to @next (fastify#197)

Author: simoneb

.github/workflows/ci.yml

@@ -21,7 +21,6 @@ jobs:
     needs: test
     runs-on: ubuntu-latest
     steps:
-      - uses: fastify/github-action-merge-dependabot@v1.2.1
-        if: ${{ github.actor == 'dependabot[bot]' && github.event_name == 'pull_request' }}
+      - uses: fastify/github-action-merge-dependabot@next
         with:
-          github-token: ${{secrets.github_token}}
+          github-token: ${{ secrets.GITHUB_TOKEN }}