ci: Pin GitHub Actions to full-length commit SHAs (#1402)

Author: danfiedler-msft

.github/workflows/conflicting-pr-label.yml

@@ -21,7 +21,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     - name: check if prs are dirty
-      uses: eps1lon/actions-label-merge-conflict@releases/2.x
+      uses: eps1lon/actions-label-merge-conflict@0273be72a0bbd58fcd71d0d6c02c209b50d1e5e1 # v3.1.0
       if: env.LABELING_TOKEN != '' && env.LABELING_TOKEN != null
       id: check
       with: