Bump actions/checkout from 5 to 6

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] <support@github.com>

Author: dependabot[bot]

.github/workflows/dependabot.yml

@@ -18,7 +18,7 @@ jobs:
 
     name: Appraisal - Ruby ${{ matrix.ruby-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           ref: ${{ github.head_ref }}
       - name: Set up Ruby ${{ matrix.ruby-version }}

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
       BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/rails_${{ matrix.rails-version }}.gemfile
     environment: release
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/steep.yml

@@ -20,7 +20,7 @@ jobs:
 
     name: Steep - Ruby ${{ matrix.ruby-version }} on Rails ${{ matrix.rails-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby ${{ matrix.ruby-version }} on Rails ${{ matrix.rails-version }}
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/tests.yml

@@ -40,7 +40,7 @@ jobs:
 
     name: Specs - Ruby ${{ matrix.ruby-version }} on Rails ${{ matrix.rails-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby ${{ matrix.ruby-version }} on Rails ${{ matrix.rails-version }}
         uses: ruby/setup-ruby@v1
         with: