Bump actions/checkout from 1 to 3 (#19)

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 3.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v1...v3)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -29,7 +29,7 @@ jobs:
           # MacOS not available on x86
           - {os: 'macOS-latest', arch: 'x86'}
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
       - uses: julia-actions/setup-julia@latest
         with:
           version: ${{ matrix.version }}