Bump actions/checkout from 4 to 5 (#4574)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  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>

.github/workflows/merge.yml

@@ -28,7 +28,7 @@ jobs:
     # Don't run on closed unmerged pull requests, or pull requests with the "breaking" label
     if: github.event.pull_request.merged && !contains(github.event.pull_request.labels.*.name, 'breaking')
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Create backport pull requests
         uses: korthout/backport-action@v3
 
@@ -38,7 +38,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - run: sudo apt-get update
       - run: sudo apt install libwebkit2gtk-4.1-dev libgtk-3-dev libayatana-appindicator3-dev libxdo-dev libglib2.0-dev
       - uses: dtolnay/rust-toolchain@nightly
@@ -75,7 +75,7 @@ jobs:
 #     options: --security-opt seccomp=unconfined
 #   steps:
 #     - name: Checkout repository
-#       uses: actions/checkout@v4
+#       uses: actions/checkout@v5
 #     - name: Generate code coverage
 #       run: |
 #         apt-get update &&\