Bump actions/checkout from 3 to 4 (#1091)

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>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Rachel Brindle <you@subluminal.net>

Author: dependabot[bot]

.github/workflows/ci-swiftpm.yml

@@ -55,7 +55,7 @@ jobs:
     name: SwiftPM, Windows
     runs-on: windows-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Swift
         uses: compnerd/gha-setup-swift@main
         with: