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/publish.yml

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

.github/workflows/test.yml

@@ -45,7 +45,7 @@ jobs:
       shell: bash
       run: |
         jackd --no-realtime -d dummy &
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
     - uses: astral-sh/setup-uv@v7
     - name: Install (editable) Python package
       run: |
@@ -57,7 +57,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
       with:
         fetch-depth: 0
     - name: Double-check Python version