Bump actions/checkout from 4 to 6 (#205)

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  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>
Co-authored-by: Bart van de Lint <33758964+1-Bart-1@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -40,7 +40,7 @@ jobs:
             version: 1
             build_is_production_build: true
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
@@ -76,7 +76,7 @@ jobs:
           - ubuntu-latest
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: julia-actions/setup-julia@v2
       with:
         arch: ${{ matrix.julia_arch }}
@@ -106,7 +106,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 40
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
       - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1

.github/workflows/setup-test.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 40
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'