Use uv to set up python version in tests (#574)

* Add free-thread Python 3.13 and preview Python 3.14 to test matrix
* Setup python with uv?
* No system uv

Author: ponyisi

.github/workflows/ci.yaml

@@ -37,18 +37,15 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-
       - name: Install uv
         uses: astral-sh/setup-uv@v5
+        with:
+          python-version: ${{ matrix.python-version }}
 
       - name: Install dependencies
         run: |
-          uv pip install --system --upgrade '.[test,docs]'
-          uv pip list --system
+          uv pip install --upgrade '.[test,docs]'
+          uv pip list
 
       - name: Test with pytest
         run: |