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/test.yml

@@ -148,7 +148,7 @@ jobs:
     env: # $BUNDLE_GEMFILE must be set at the job level, so it is set for all steps
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup Bundler 1.x for Rails 4.x
         if: ${{ matrix.gemfile == 'gemfiles/Gemfile-rails-4-1' || matrix.gemfile == 'gemfiles/Gemfile-rails-4-2' }}
         run: echo "BUNDLER_VERSION=1.17.3" >> $GITHUB_ENV