Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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]>

Author: dependabot[bot]

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
     name: Check style
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: chartboost/ruff-action@v1
     - uses: chartboost/ruff-action@v1
       with:
@@ -22,7 +22,7 @@ jobs:
     permissions:
       id-token: write
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Install uv
       uses: astral-sh/setup-uv@v4
       with:

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
     name: Check style
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: astral-sh/ruff-action@v1
     - uses: astral-sh/ruff-action@v1
       with:
@@ -27,7 +27,7 @@ jobs:
     name: Run tests (Python ${{ matrix.python-version }})
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Install uv
       uses: astral-sh/setup-uv@v4
     - name: Build