Bump actions/checkout from 5 to 6 (#66)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/breakage.yml

@@ -24,7 +24,7 @@ jobs:
         pkgversion: [latest]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # Install Julia
       - uses: julia-actions/setup-julia@v2

.github/workflows/ci-julia-nightly.yml

@@ -25,7 +25,7 @@ jobs:
             threads: 2
             jet: 'true'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/install-juliaup@v2
         with:
           channel: ${{ matrix.version }}~${{ matrix.arch }}

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
         arch:
           - x64
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}

.github/workflows/downgrade.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         version: ['1.10']
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v1
         with:
           version: ${{ matrix.version }}