fix(database,ios): close the update completion handlers

The closures were closed before their bodies, so the file did not compile and update never completed.

Author: SelaseKay

packages/firebase_database/firebase_database/ios/firebase_database/Sources/firebase_database/FLTFirebaseDatabasePlugin.swift

@@ -270,7 +270,7 @@ public class FLTFirebaseDatabasePlugin: NSObject, FlutterPlugin, FLTFirebasePlug
 
     let values = request.value.compactMapValues { $0 }
 
-    reference.updateChildValues(values) { error, _ in }
+    reference.updateChildValues(values) { error, _ in
       if let error {
         completion(.failure(self.createFlutterError(error)))
       } else {
@@ -463,7 +463,7 @@ public class FLTFirebaseDatabasePlugin: NSObject, FlutterPlugin, FLTFirebasePlug
 
     let values = request.value.compactMapValues { $0 }
 
-    reference.onDisconnectUpdateChildValues(values) { error, _ in }
+    reference.onDisconnectUpdateChildValues(values) { error, _ in
       if let error {
         completion(.failure(self.createFlutterError(error)))
       } else {