build(deps): 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/github-pages.yml

@@ -10,7 +10,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ruby

.github/workflows/push_gem.yml

@@ -31,7 +31,7 @@ jobs:
         with:
           egress-policy: audit
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1

.github/workflows/sync-ruby.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'ruby' }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Create GitHub App token
         id: app-token

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
 
     steps: &test-steps
       - name: repo checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: load ruby
         uses: ruby/setup-ruby@v1
@@ -120,7 +120,7 @@ jobs:
           - { openssl: aws-lc-latest, skip-warnings: true }
     steps:
       - name: repo checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - id: cache-openssl
         uses: actions/cache@v4