Bump actions/checkout from 6 to 7 (#137)

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  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/DocPreviewsCleanup.yml

@@ -17,7 +17,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           ref: gh-pages
       - name: Delete preview and history + push changes

.github/workflows/Documentation.yml

@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: julia-actions/setup-julia@v3
         with:
           version: "1"
@@ -74,7 +74,7 @@ jobs:
       # Have only one job pushing the docs at a time.
       group: docs-pushing
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: julia-actions/setup-julia@v3
         with:
           version: "1"

.github/workflows/UnitTests.yml

@@ -53,7 +53,7 @@ jobs:
             julia-arch: x86
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: julia-actions/setup-julia@v3
         with:
           version: ${{ matrix.julia-version }}