ci: bump actions/checkout from 4 to 5

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](actions/checkout@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] <[email protected]>

Author: dependabot[bot]

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     steps:
       - name: Set up repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Set up tree-sitter
         uses: tree-sitter/setup-action@v2
@@ -32,7 +32,7 @@ jobs:
         uses: tree-sitter/parser-test-action@v2
 
       - name: Clone neovim runtime corpus
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
         with:
           repository: neovim/neovim
           path: .tests/neovim