chore: align usage of actions/checkout version pin

Author: xmatthias

.github/workflows/zizmor.yml

@@ -22,7 +22,7 @@ jobs:
       # actions: read # only needed for private repos
     steps:
       - name: Checkout repository
-        uses: actions/checkout@c2d88d3ecc89a9ef08eebf45d9637801dcee7eb5 # v5.0.1
+        uses: actions/checkout@v6.0.0
         with:
           persist-credentials: false