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

@@ -20,13 +20,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
-        pyqt-version: [5.12.3, 5.15.9]
-        exclude:
-          - pyqt-version: 5.12.3
-            python-version: 3.11
-          - pyqt-version: 5.12.3
-            python-version: 3.12
+        python-version: ['3.8', '3.9', '3.10']
+        pyqt-version: [5.12.3]
     env:
       DISPLAY: ':99.0'
       QT_MAC_WANTS_LAYER: 1  # PyQT gui tests involving qtbot interaction on macOS will fail without this
@@ -40,16 +35,19 @@ jobs:
         miniforge-variant: Miniforge3
         miniforge-version: latest
         activate-environment: pydm-env
+    - name: Install pyqt with mamba
+      shell: bash -el {0}
+      run: |
+        mamba install pyqt=${{ matrix.pyqt-version }}
     - name: Install python packages
       shell: bash -el {0}
       run: |
         if [ "$RUNNER_OS" == "Windows" ]; then
-          mamba install pyqt=${{ matrix.pyqt-version }}
-          mamba install --file requirements.txt --file windows-dev-requirements.txt
+          python -m pip install -r requirements.txt -r windows-dev-requirements.txt
         else
-          mamba install pyqt=${{ matrix.pyqt-version }} $(cat requirements.txt dev-requirements.txt)
+          python -m pip install -r requirements.txt -r dev-requirements.txt
         fi
-    - name: Install packages for testing a pyqt app on linux
+    - name: Install packages for testing a pyqt app on linux, start the display server + window manager
       shell: bash -el {0}
       run: |
         if [ "$RUNNER_OS" == "Linux" ]; then