chore: harden Dependabot auto-merge (#155)

Author: sadjow

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

@@ -1,7 +1,7 @@
 name: Dependabot auto-merge
 
 on:
-  pull_request:
+  pull_request_target:
     types: [opened, synchronize, reopened]
 
 permissions:
@@ -17,7 +17,7 @@ jobs:
     steps:
       - name: Read Dependabot metadata
         id: metadata
-        uses: dependabot/fetch-metadata@d7267f607e9d3fb96fc2fbe83e0af444713e90b7
+        uses: dependabot/fetch-metadata@25dd0e34f4fe68f24cc83900b1fe3fe149efef98 # v3.1.0
         with:
           github-token: '${{ secrets.GITHUB_TOKEN }}'