fix(predictions): update liveness websocket send event to be synchronous (#3693)

Author: phantumcode

AmplifyPlugins/Predictions/AWSPredictionsPlugin/Liveness/Service/FaceLivenessSession.swift

@@ -84,7 +84,7 @@ public final class FaceLivenessSession: LivenessService {
         _ event: LivenessEvent<T>,
         eventDate: @escaping () -> Date = Date.init
     ) {
-        livenessServiceDispatchQueue.async {
+        livenessServiceDispatchQueue.sync {
             let encodedPayload = self.eventStreamEncoder.encode(
                 payload: event.payload,
                 headers: [