MNT: make gh actions install python dependencies using pip, so correc…

…t version is installed

For gh actions setup we were passing pip package lists for conda to
install, but this causes us to install old p4p package which only
supports python <=3.10. So need newer p4p from pip to run with newer
python.

.github/workflows/run-tests.yml

@@ -43,11 +43,10 @@ jobs:
     - name: Install python packages
       shell: bash -el {0}
       run: |
+        python -m pip install --upgrade pip
+        python -m pip install pyqt${{ matrix.pyqt-version }} -r requirements.txt -r dev-requirements.txt
         if [ "$RUNNER_OS" == "Windows" ]; then
-          mamba install pyqt=${{ matrix.pyqt-version }}
-          mamba install --file requirements.txt --file windows-dev-requirements.txt
-        else
-          mamba install pyqt=${{ matrix.pyqt-version }} $(cat requirements.txt dev-requirements.txt)
+          python -m pip install -r windows-dev-requirements.txt
         fi
     - name: Install packages for testing a pyqt app on linux
       shell: bash -el {0}