Bump actions/checkout from 4.2.2 to 6.0.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.2.2 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4.2.2...v6.0.0)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     if: github.repository_owner == 'nix-community'
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4.2.2
+      uses: actions/checkout@v6.0.0
 
     - name: Install Nix
       uses: cachix/install-nix-action@v31
@@ -50,7 +50,7 @@ jobs:
     if: github.repository_owner == 'nix-community'
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4.2.2
+      uses: actions/checkout@v6.0.0
 
     - name: Install Nix
       uses: cachix/install-nix-action@v31

.github/workflows/pulls.yml

@@ -10,7 +10,7 @@ jobs:
     outputs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v4.2.2
+      - uses: actions/checkout@v6.0.0
       - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable