Bump actions/checkout from 1 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/main.yml

@@ -61,7 +61,7 @@ jobs:
           git -C /home/opam/opam-repository pull origin master && HOME=/home/opam opam update -y
       - name: Checkout repository
         # See https://github.com/actions/checkout/issues/334
-        uses: actions/checkout@v1
+        uses: actions/checkout@v4
       - name: Setup repo and install dependencies
         run: |
           sudo chown -R opam:opam .