[mac][Qt] Remove old Qt versions (incompatible architecture for '5.15.0', '6.0.4', '6.1.0')

Author: Jarod42

.github/workflows/premake5-qt-mac-xcode4.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        qt-version: ['5.15.0', '6.0.4', '6.1.0', '6.7.0']
+        qt-version: ['6.9.0']
 
     steps:
     - name: Checkout