ci: use explicit version for fetch-metadata version comment (#1633)

ci: use explicit version

Author: wochinge

.github/workflows/dependabot-merge.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - name: Dependabot metadata
         id: metadata
-        uses: dependabot/fetch-metadata@ffa630c65fa7e0ecfa0625b5ceda64399aea1b36 # v3
+        uses: dependabot/fetch-metadata@ffa630c65fa7e0ecfa0625b5ceda64399aea1b36 # v3.0.0
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"
       - name: Enable auto-merge for Dependabot PRs