fix: downgrade checkout

...to avoid usage of node24 - not supported from stackit right now

checkout/action.yml

@@ -33,9 +33,9 @@ runs:
   using: composite
   steps:
     # Pinned to commit SHA instead of a tag to prevent supply chain attacks.
-    # actions/checkout v6.0.2 — https://code.forgejo.org/actions/checkout/commits/tag/v6.0.2
+    # actions/checkout v5.0.1 — https://code.forgejo.org/actions/checkout/commits/tag/v5.0.1
     - name: Checkout repository
-      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+      uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd
       with:
         ref: ${{ inputs.ref }}
         repository: ${{ inputs.repository }}