Bump actions/checkout from 3 to 4 (#391)

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>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -49,7 +49,7 @@ jobs:
             arch: 'x64'
             llvm_args: '--opaque-pointers'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0  # build_ci.jl needs to be able to inspect the git log
 
@@ -110,7 +110,7 @@ jobs:
         arch: ['x64']
         llvm_args: ['', '--opaque-pointers']
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0  # build_ci.jl needs to be able to inspect the git log
 
@@ -154,7 +154,7 @@ jobs:
     name: Documentation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@latest
         with:
           version: '1.8'