Use the Dummy audio driver in the project manager

This prevents Godot from appearing in the list of applications
outputting sound in the OS while the user is in the project manager.

main/main.cpp

@@ -2338,7 +2338,14 @@ Error Main::setup(const char *execpath, int argc, char *argv[], bool p_second_ph
 
 	GLOBAL_DEF_RST_NOVAL("audio/driver/driver", AudioDriverManager::get_driver(0)->get_name());
 	if (audio_driver.is_empty()) { // Specified in project.godot.
-		audio_driver = GLOBAL_GET("audio/driver/driver");
+		if (project_manager) {
+			// The project manager doesn't need to play sound (TTS audio output is not emitted by Godot, but by the system itself).
+			// Disable audio output so it doesn't appear in the list of applications outputting sound in the OS.
+			// On macOS, this also prevents the project manager from inhibiting suspend.
+			audio_driver = "Dummy";
+		} else {
+			audio_driver = GLOBAL_GET("audio/driver/driver");
+		}
 	}
 
 	// Make sure that dummy is the last one, which it is assumed to be by design.