release _latestState

Author: justinmc

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -514,6 +514,7 @@ - (void)dealloc {
   [_selectedTextRange release];
   [_tokenizer release];
   [_autofillId release];
+  [_latestState release];
   [super dealloc];
 }