Install Qt 6

.github/workflows/mac.yml

@@ -15,6 +15,14 @@ jobs:
         with:
           submodules: true
           fetch-depth: 0
+      - name: Install Qt
+        uses: jurplel/install-qt-action@v4
+        with:
+          version: '6.7.3'
+          host: 'mac'
+          arch: 'clang_64'
+          setup-python: false
+          modules: 'qtcharts qtscxml qt5compat qtlocation qtmultimedia qtpositioning qtserialport qtspeech qtwebsockets qtwebengine qtshadertools'
       - name: Configure SDRangel
         run: |
           mkdir build && cd build