ci(deps): update actions/checkout action to v5

Author: Renovate Bot

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
     timeout-minutes: 30
     steps:
       - name: Checkout the repo
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
       - name: Check Nix flake inputs
         uses: DeterminateSystems/flake-checker-action@v12
       - name: Install Nix