Bump astral-sh/setup-uv from 3 to 6

Bumps [astral-sh/setup-uv](https://github.com/astral-sh/setup-uv) from 3 to 6.
- [Release notes](https://github.com/astral-sh/setup-uv/releases)
- [Commits](astral-sh/setup-uv@v3...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/ci.yml

@@ -44,7 +44,7 @@ jobs:
       # Minimum supported python here.
     - run: echo 'UV_PYTHON=3.9' | tee -a "${GITHUB_ENV}"
     - name: Setup uv
-      uses: astral-sh/setup-uv@v3
+      uses: astral-sh/setup-uv@v6
     - run: ./script/init.sh
 
     - name: Setup Node.js for pyright