Bump actions/checkout from 6 to 7

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>

Author: dependabot[bot]

.github/workflows/html-macos.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: macos-latest
     steps:
     - name: Clone repo
-      uses: actions/checkout@v6
+      uses: actions/checkout@v7
       with:
         fetch-depth: 0
     - name: Install pandoc

.github/workflows/linkcheck.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Clone repo
-      uses: actions/checkout@v6
+      uses: actions/checkout@v7
       with:
         fetch-depth: 0
     - name: Install pandoc

.github/workflows/publish.yml

@@ -7,7 +7,7 @@ jobs:
     name: Build distribution
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
     - name: Install uv
       uses: astral-sh/setup-uv@v7
     - name: Build a binary wheel and a source tarball

.github/workflows/version-matrix.yml

@@ -42,7 +42,7 @@ jobs:
     env: ${{ matrix.env || fromJSON('{}') }}
     steps:
     - name: Clone repo
-      uses: actions/checkout@v6
+      uses: actions/checkout@v7
       with:
         fetch-depth: 0
     - name: Install apt packages