pull-request: use standard pip install

Author: tschaume

.github/workflows/pull-request.yml

@@ -25,9 +25,9 @@ jobs:
         run: sudo apt-get update && sudo apt-get install chromium-chromedriver
       - name: Install dependencies
         run: |
-          python${{ matrix.python-version }} -m pip install --upgrade pip pip-tools
+          python${{ matrix.python-version }} -m pip install --upgrade pip
           python${{ matrix.python-version }} -m pip install `grep numpy== requirements/ubuntu-latest_py${{ matrix.python-version }}_extras.txt`
-          python${{ matrix.python-version }} -m piptools sync requirements/ubuntu-latest_py${{ matrix.python-version }}_extras.txt
+          python${{ matrix.python-version }} -m pip install -r requirements/ubuntu-latest_py${{ matrix.python-version }}_extras.txt
           python${{ matrix.python-version }} -m pip install --no-deps .
       - name: Test modules
         run: python${{ matrix.python-version }} -m pytest tests