Bump actions/checkout from 5 to 6

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] <support@github.com>

Author: dependabot[bot]

.github/workflows/Breakage.yml

@@ -18,7 +18,7 @@ jobs:
         pkgversion: [latest, stable]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       # Install Julia
       - uses: julia-actions/setup-julia@v2
@@ -88,7 +88,7 @@ jobs:
     needs: break
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: actions/download-artifact@v7
         with:

.github/workflows/CI.yml

@@ -43,7 +43,7 @@ jobs:
             os: windows-latest
             arch: x64
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
@@ -65,7 +65,7 @@ jobs:
     name: Documentation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1'

.github/workflows/DocPreviewCleanup.yml

@@ -16,7 +16,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes