build(deps): bump astral-sh/setup-uv from 5 to 6

Bumps [astral-sh/setup-uv](https://github.com/astral-sh/setup-uv) from 5 to 6.
- [Release notes](https://github.com/astral-sh/setup-uv/releases)
- [Commits](astral-sh/setup-uv@v5...v6)

---
updated-dependencies:
- dependency-name: astral-sh/setup-uv
  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/test.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
-    - uses: astral-sh/setup-uv@v5
+    - uses: astral-sh/setup-uv@v6
       with:
         python-version: ${{ matrix.python-version }}
         # TODO(https://github.com/astral-sh/setup-uv/issues/226): Remove this.