Fix docs CI: use venv for uv to fix 'failed to create directory' (#4460)

Use venv for uv to fix 'failed to create directory'

.github/workflows/doc.yml

@@ -32,8 +32,9 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install uv
-          python -m uv pip install --system -e ".[d]"
-          python -m uv pip install --system -r "docs/requirements.txt"
+          python -m uv venv
+          python -m uv pip install -e ".[d]"
+          python -m uv pip install -r "docs/requirements.txt"
 
       - name: Build documentation
         run: sphinx-build -a -b html -W --keep-going docs/ docs/_build