Fix CI: Use uv run for pytest to access venv packages

Amp-Thread-ID: https://ampcode.com/threads/T-1f1f15f6-c4ef-4e6e-896a-67a085d602b0
Co-authored-by: Amp <[email protected]>

Author: vinitkumar

.github/workflows/pythonpackage.yml

@@ -72,7 +72,7 @@ jobs:
 
     - name: Run tests
       run: |
-        pytest --cov=json2xml --cov-report=xml:coverage/reports/coverage.xml --cov-report=term -xvs tests -n auto
+        uv run pytest --cov=json2xml --cov-report=xml:coverage/reports/coverage.xml --cov-report=term -xvs tests -n auto
       env:
         PYTHONPATH: ${{ github.workspace }}