ci: Move Python 3.11 job to Ubuntu 22.04

This will allow dropping the pin on PyQt6, since glibc will be new
enough. Additionally, that release has GTK4, so we can start testing
that properly now.

Author: QuLogic

.github/workflows/tests.yml

@@ -73,10 +73,8 @@ jobs:
             pyqt6-ver: '!=6.5.1'
             # https://bugreports.qt.io/projects/PYSIDE/issues/PYSIDE-2346
             pyside6-ver: '!=6.5.1'
-          - os: ubuntu-20.04
+          - os: ubuntu-22.04
             python-version: '3.11'
-            # https://github.com/matplotlib/matplotlib/pull/26052#issuecomment-1574595954
-            pyqt6-ver: '!=6.5.1'
             # https://bugreports.qt.io/projects/PYSIDE/issues/PYSIDE-2346
             pyside6-ver: '!=6.5.1'
             extra-requirements: '-r requirements/testing/extra.txt'
@@ -139,7 +137,9 @@ jobs:
               texlive-xetex \
               ttf-wqy-zenhei
             if [[ "${{ matrix.os }}" = ubuntu-20.04 ]]; then
-              sudo apt install -yy libopengl0
+              sudo apt-get install -yy libopengl0
+            else  # ubuntu-22.04
+              sudo apt-get install -yy gir1.2-gtk-4.0 libnotify4
             fi
             ;;
           macOS)
@@ -180,10 +180,10 @@ jobs:
             ~/.cache/matplotlib
             !~/.cache/matplotlib/tex.cache
             !~/.cache/matplotlib/test_cache
-          key: 2-${{ runner.os }}-py${{ matrix.python-version }}-mpl-${{ github.ref }}-${{ github.sha }}
+          key: 3-${{ runner.os }}-py${{ matrix.python-version }}-mpl-${{ github.ref }}-${{ github.sha }}
           restore-keys: |
-            2-${{ runner.os }}-py${{ matrix.python-version }}-mpl-${{ github.ref }}-
-            2-${{ runner.os }}-py${{ matrix.python-version }}-mpl-
+            3-${{ runner.os }}-py${{ matrix.python-version }}-mpl-${{ github.ref }}-
+            3-${{ runner.os }}-py${{ matrix.python-version }}-mpl-
 
       - name: Install Python dependencies
         run: |
@@ -233,7 +233,7 @@ jobs:
               echo 'PySide2 is available' ||
               echo 'PySide2 is not available'
           fi
-          if [[ "${{ matrix.os }}" = ubuntu-20.04 ]]; then
+          if [[ "${{ runner.os }}" != 'macOS' ]]; then
             python -mpip install --upgrade pyqt6${{ matrix.pyqt6-ver }} &&
               python -c 'import PyQt6.QtCore' &&
               echo 'PyQt6 is available' ||