Always get a qt backend in local venv, ignoring runner site-packages

Author: hosaka

.github/workflows/main.yml

@@ -32,11 +32,13 @@ jobs:
           - os: macos-arm64
             image: macos-14
         exclude:
+          # pyside2 does not publish arm64 packages
           - os: macos-arm64
             qt-version: pyside2
+          # pyside2 requires python <3.11
           - python-version: "3.11"
             qt-version: pyside2
-          # both pyside6 and pyqt6 require python>=3.9
+          # pyside6 and pyqt6 require python >=3.9
           - python-version: "3.8"
             qt-version: pyside6
           - python-version: "3.8"
@@ -104,7 +106,7 @@ jobs:
       #   run: poetry run mypy
 
       - name: Install Qt
-        run: poetry run pip install ${{ matrix.qt-version }}
+        run: poetry run pip install --ignore-installed ${{ matrix.qt-version }}
 
       - name: Install libxcb dependencies
         if: ${{ matrix.os == 'ubuntu' }}