fixed ios build support

plugin.xml

@@ -102,6 +102,13 @@
         <framework src="NetworkExtension.framework" />
         <framework src="LocalAuthentication.framework" />
         <framework src="UserNotifications.framework" />
-        <framework src="Firebase/Messaging" type="podspec" spec="$IOS_FIREBASE_MESSAGING_VERSION" />
+        <podspec>
+            <config>
+                <source url="https://cdn.cocoapods.org/" />
+            </config>
+            <pods>
+                <pod name="Firebase/Messaging" spec="$IOS_FIREBASE_MESSAGING_VERSION" />
+            </pods>
+        </podspec>
     </platform>
 </plugin>