Bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  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

@@ -18,7 +18,7 @@ jobs:
       matrix:
         ruby: ["3.3", "3.4"]
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -38,7 +38,7 @@ jobs:
       run:
         working-directory: docs
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -73,7 +73,7 @@ jobs:
       matrix:
         ruby: ["3.3", "3.4"]
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -88,7 +88,7 @@ jobs:
     name: MCP registry up to date
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -113,7 +113,7 @@ jobs:
       contents: read
       packages: write
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v4
         with: