bump ios dependency to 5.2.13

Author: nan-li

ios/onesignal_flutter.podspec

@@ -13,7 +13,7 @@ Pod::Spec.new do |s|
   s.source_files = 'Classes/**/*'
   s.public_header_files = 'Classes/**/*.h'
   s.dependency 'Flutter'
-  s.dependency 'OneSignalXCFramework', '5.2.12'
+  s.dependency 'OneSignalXCFramework', '5.2.13'
   s.ios.deployment_target = '11.0'
   s.static_framework = true
 end