fix qt version for macOS

setup.py

@@ -123,9 +123,12 @@ def main():
     ] + (["-DOPENCV_EXTRA_MODULES_PATH=" + os.path.abspath("opencv_contrib/modules")] if build_contrib else [])
 
     # OS-specific components
-    if (sys.platform == 'darwin' or sys.platform.startswith('linux')) and not build_headless:
+    if sys.platform.startswith('linux') and not build_headless:
         cmake_args.append("-DWITH_QT=4")
 
+    if sys.platform == 'darwin' and not build_headless:
+        cmake_args.append("-DWITH_QT=5")
+
     if build_headless:
         # it seems that cocoa cannot be disabled so on macOS the package is not truly headless
         cmake_args.append("-DWITH_WIN32UI=OFF")