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)
- [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/libyaml.yml

@@ -27,7 +27,7 @@ jobs:
     steps:
       - name: Install libraries
         run: sudo apt install haveged
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/push_gem.yml

@@ -31,7 +31,7 @@ jobs:
         with:
           egress-policy: audit
 
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@d5126b9b3579e429dd52e51e68624dda2e05be25 # v1.267.0

.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

@@ -39,7 +39,7 @@ jobs:
           # CRuby < 2.6 does not support macos-arm64
           - { os: macos-latest, ruby: 2.5 }
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby-pkgs@v1
         with:
@@ -71,7 +71,7 @@ jobs:
           - os: ubuntu-24.04-ppc64le
           - os: ubuntu-24.04-s390x
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         run: |
           sudo apt-get update