Don't block dependabot PRs

Author: cyqsimon

.github/workflows/require-changelog-for-PRs.yml

@@ -7,6 +7,8 @@ jobs:
   check-changelog:
     name: Check for changelog entry
     runs-on: ubuntu-latest
+    # dependabot PRs are automerged if CI passes; we shouldn't block these
+    if: ${{ !startsWith(github.head_ref, 'dependabot/') }}
     env:
       PR_SUBMITTER: ${{ github.actor }}
       PR_NUMBER: ${{ github.event.number }}