Use commit SHA instead of branch name for third-party actions

Author: andreaTP

.github/workflows/conflictDetector.yaml

@@ -6,7 +6,7 @@ jobs:
   triage:
     runs-on: ubuntu-latest
     steps:
-      - uses: mschilde/auto-label-merge-conflicts@master
+      - uses: mschilde/auto-label-merge-conflicts@8c6faa8a252e35ba5e15703b3d747bf726cdb95c
         with:
           CONFLICT_LABEL_NAME: "has conflicts"
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}