Bump actions/checkout from 5 to 6 (#405)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci-nix.yml

@@ -25,7 +25,7 @@ jobs:
     runs-on: ubuntu-24.04
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: cachix/install-nix-action@0b0e072294b088b73964f1d72dfdac0951439dbd # v31.8.4
         with:
           extra_nix_config: |

.github/workflows/ci-ruby.yml

@@ -41,7 +41,7 @@ jobs:
       # https://github.com/kachick/irb-power_assert/blob/104834846baf5caa1e8536a11c43acdd56fc849c/CONTRIBUTING.md#adding-dependencies-for-this-gem
       BUNDLE_WITHOUT: development
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
@@ -54,7 +54,7 @@ jobs:
   rubocop:
     runs-on: 'ubuntu-24.04'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           bundler-cache: true

.github/workflows/dependency-review.yml

@@ -13,6 +13,6 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: 'Checkout Repository'
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: 'Dependency Review'
         uses: actions/dependency-review-action@v4

.github/workflows/lint.yml

@@ -11,7 +11,7 @@ jobs:
     timeout-minutes: 15
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: dprint/[email protected]
         with:
           dprint-version: '0.50.2' # selfup {"extract":"\\d[^']+","replacer":["bash","-c","dprint --version | cut -d ' ' -f 2"]}
@@ -20,7 +20,7 @@ jobs:
     timeout-minutes: 15
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: crate-ci/[email protected] # selfup {"extract":"\\d\\.\\d+\\.\\d+","replacer":["bash","-c","typos --version | cut -d ' ' -f 2"]}
         with:
           files: |

.github/workflows/release.yml

@@ -26,7 +26,7 @@ jobs:
   build:
     runs-on: 'ubuntu-24.04'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           bundler-cache: true
@@ -52,7 +52,7 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/')
     steps:
       # Required to checkout for gh command
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Dowbload prebuild assets
         run: |
           gh run download '${{ github.run_id }}'
@@ -82,7 +82,7 @@ jobs:
       GH_TOKEN: ${{ github.token }}
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with: