fix: update 'pavelzw/pytest-action' to use uv

Author: feeph

.github/workflows/validate-code.yaml

@@ -83,13 +83,12 @@ jobs:
           python-version: ${{ matrix.python-version }}
       - name: install uv
         uses: astral-sh/setup-uv@v7
+      - name: install dependencies
         with:
           python-version: ${{ matrix.python-version }}
-      - name: install dependencies
-        env:
-          UV_SYSTEM_PYTHON: 1
         run: |
-          uv sync --locked --all-extras --dev
+          uv export --format=requirements.txt --all-extras --dev --group=dev > requirements.txt
+          pip install -r requirements.txt
       # https://github.com/marketplace/actions/run-pytest
       - name: perform unit tests (Python ${{ matrix.python-version }})
         env: