only use uv python

Author: pjbull

.github/workflows/tests.yml

@@ -48,6 +48,7 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           activate-environment: true
+          python-preference: "only-managed"
 
       - name: Install dependencies (Python 3.14)
         if: matrix.python-version == '3.14'