Create and enter 'uv' virtual environment for tests

Author: theolujay

.github/workflows/tests.yml

@@ -27,6 +27,8 @@ jobs:
               run: |
                 python -m pip install --upgrade pip
                 pip install uv
+                uv venv
+                uv source venv/bin/activate
                 uv pip install -e ".[dev]"
                 uv pip install pytest pytest-cov