Update actions/checkout digest to cbb7224 (#256)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/slsa.yml

@@ -25,7 +25,7 @@ jobs:
         shell: bash
 
       - name: Checkout repository
-        uses: actions/checkout@3b9b8c884f6b4bb4d5be2779c26374abadae0871 # master
+        uses: actions/checkout@cbb722410c2e876e24abbe8de2cc27693e501dcb # master
 
       - name: Build artifacts
         run: |