MNT: make gh actions setup use conda and pip to install packages

Before it was using the pip '.txt' package files to install things
using conda instead. But this doesn't mimic how users locally install
packages with conda+pip, and some packages in coda (ex=p4p) are outdated
compared to pip.

.github/workflows/run-tests.yml

@@ -35,26 +35,35 @@ jobs:
         miniforge-variant: Miniforge3
         miniforge-version: latest
         activate-environment: pydm-env
-    - name: Install python packages
+
+    - name: Install PyDM with Mamba
+      shell: bash -el {0}
+      run: |
+        mamba install -c conda-forge pydm pyqt=${{ matrix.pyqt-version }}
+
+    - name: Install additional Python dependencies with pip
       shell: bash -el {0}
       run: |
+        pip install -r requirements.txt
         if [ "$RUNNER_OS" == "Windows" ]; then
-          mamba install pyqt=${{ matrix.pyqt-version }}
-          mamba install --file requirements.txt --file windows-dev-requirements.txt
+          pip install -r windows-dev-requirements.txt
         else
-          mamba install pyqt=${{ matrix.pyqt-version }} $(cat requirements.txt dev-requirements.txt)
+          pip install -r dev-requirements.txt
         fi
-    - name: Install packages for testing a pyqt app on linux
+
+    - name: Install packages for testing a PyQt app on Linux
       shell: bash -el {0}
       run: |
         if [ "$RUNNER_OS" == "Linux" ]; then
-          sudo apt install xvfb herbstluftwm libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0 x11-utils
+          sudo apt update
+          sudo apt install -y xvfb herbstluftwm libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0 x11-utils
           sudo /sbin/start-stop-daemon --start --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -screen 0 1024x768x24 -ac +extension GLX +render -noreset
           sleep 3
           sudo /sbin/start-stop-daemon --start --pidfile /tmp/custom_herbstluftwm_99.pid --make-pidfile --background --exec /usr/bin/herbstluftwm
           sleep 1
         fi
+
     - name: Test with pytest
       shell: bash -el {0}
       run: |
-        python run_tests.py
+        python run_tests.py