fix: ensure webview becomes tranparent (#238)

Since a while it seems there is a race condition problem where the
webview doesn't get setup in time. This seems to occur because of either
A) a OTA update from Maps itself or B) an iOS update

ios/Plugin/Plugin.swift

@@ -73,6 +73,10 @@ public class CapacitorGoogleMaps: CustomMapViewEvents {
 
             customMapView.GMapView.delegate = customMapView;
             self.customWebView?.customMapViews[customMapView.id] = customMapView
+
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
+                self.setupWebView()
+            }
         }
     }