Fixed Tween::start() with pending updates

Start was canceled instead of deferred in case of an update in progress.
Fixes #35441

scene/animation/tween.cpp

@@ -827,6 +827,7 @@ bool Tween::start() {
 	// Are there any pending updates?
 	if (pending_update != 0) {
 		// Start the tweens after deferring
+		call_deferred("start");
 		return true;
 	}