Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
     name: "Tests: Ruby ${{ matrix.ruby }}"
     steps:
     - name: Clone Repo
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Setup Ruby ${{ matrix.ruby }}
       uses: ruby/setup-ruby@v1
       with:
@@ -40,7 +40,7 @@ jobs:
     env:
       RUBYOPT: '-w'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}

.github/workflows/docs.yml

@@ -18,7 +18,7 @@ jobs:
     env:
       BUNDLE_WITH: "documentation"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
       - uses: ruby/setup-ruby@v1

.github/workflows/experimental.yml

@@ -22,7 +22,7 @@ jobs:
     name: "Tests: Experimental Ruby ${{ matrix.ruby }}"
     steps:
     - name: Clone Repo
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Setup Ruby ${{ matrix.ruby }}
       uses: ruby/setup-ruby@v1
       with: