ci(github-action)!: Update actions/checkout action to v4 (#14)

| datasource  | package          | from | to |
| ----------- | ---------------- | ---- | -- |
| github-tags | actions/checkout | v2   | v4 |

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Truxnell <19149206+truxnell@users.noreply.github.com>

.github/workflows/nix-lint.yaml

@@ -11,7 +11,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Install Nix
       uses: cachix/install-nix-action@v26