Bump actions/checkout from 4.2.2 to 6.0.1

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.2.2 to 6.0.1.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@11bd719...8e8c483)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
           - { ruby: ruby-head, allowed-failure: true }
     name: Test Ruby ${{ matrix.entry.ruby }}
     steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - uses: ruby/setup-ruby@0481980f17b760ef6bca5e8c55809102a0af1e5a # v1.263.0
         with:
           ruby-version: ${{ matrix.entry.ruby }}