Pin GitHub action versions

Author: garydgregory

.github/workflows/dependency-review.yml

@@ -26,9 +26,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Checkout Repository'
-        uses: actions/checkout@v4
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
       - name: 'Dependency Review PR'
-        uses: actions/dependency-review-action@v4.3.4
+        uses: actions/dependency-review-action@5a2ce3f5b92ee19cbb1541a4984c76d921601d7c # v4.3.4
         with:
           base-ref: ${{ github.event.before }}
           head-ref: ${{ github.sha }}