ci(deps): bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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/ci.yml

@@ -17,7 +17,7 @@ jobs:
         ruby-version: ['3.2', '3.3', '3.4', '4.0']
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Set up Ruby ${{ matrix.ruby-version }}
       uses: ruby/setup-ruby@v1
@@ -38,7 +38,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
 
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1

.github/workflows/copilot-setup-steps.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1

.github/workflows/create-release.yml

@@ -31,7 +31,7 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         fetch-depth: 0
 
@@ -178,7 +178,7 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     - name: Log in to GitHub Container Registry
       uses: docker/login-action@v3