ci: add checkout step to devenv tests

Author: xenOs76

.github/workflows/codeChecks.yml

@@ -50,6 +50,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
       - uses: cachix/install-nix-action@v31
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}