[StepSecurity] ci: Harden GitHub Actions (#179)

Author: step-security-bot

.github/workflows/dependabot-auto-merge.yml

@@ -13,9 +13,14 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.actor == 'dependabot[bot]' }}
     steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@ec9f2d5744a09debf3a187a3f4f675c53b671911 # v2.13.0
+        with:
+          egress-policy: audit
+
       - name: Dependabot metadata
         id: metadata
-        uses: dependabot/fetch-metadata@v2.4.0
+        uses: dependabot/fetch-metadata@08eff52bf64351f401fb50d4972fa95b9f2c2d1b # v2.4.0
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"