Bump astral-sh/setup-uv from 5.1.0 to 6.0.0

Bumps [astral-sh/setup-uv](https://github.com/astral-sh/setup-uv) from 5.1.0 to 6.0.0.
- [Release notes](https://github.com/astral-sh/setup-uv/releases)
- [Commits](astral-sh/setup-uv@v5.1.0...v6.0.0)

Author: weiji14

.github/workflows/ci_tests_legacy.yaml

@@ -79,8 +79,9 @@ jobs:
 
       # Install uv package manager
       - name: Install uv
-        uses: astral-sh/setup-uv@v5.1.0
+        uses: astral-sh/setup-uv@v6.0.0
         with:
+          activate-environment: true
           python-version: 3.11
 
       # Install the package that we want to test