Add "install Qt" to github actions: Update cmake-multi-platform.yml

.github/workflows/cmake-multi-platform.yml

@@ -47,6 +47,11 @@ jobs:
     steps:
     - uses: actions/checkout@v3
 
+    - name: Install Qt
+      uses: jurplel/install-qt-action@v3
+      version: 6.6.2
+      target: desktop
+
     - name: Set reusable strings
       # Turn repeated input strings (such as the build output directory) into step outputs. These step outputs can be used throughout the workflow file.
       id: strings