Add nuget restore

fastlane/Fastfile

@@ -37,6 +37,10 @@ platform :ios do
 
   desc 'Compile the project'
   lane :build do
+    nuget_restore(
+      project_path: 'osu.iOS.sln'
+    )
+
     souyuz(
       platform: "ios",
       build_target: "osu_iOS",

fastlane/Pluginfile

@@ -4,3 +4,4 @@
 
 gem 'fastlane-plugin-clean_testflight_testers'
 gem 'fastlane-plugin-souyuz'
+gem 'fastlane-plugin-xamarin'