Fix rake.

Author: noobs2ninjas

Rakefile

@@ -88,7 +88,7 @@ namespace :build do
       t.workspace = 'Parse.xcworkspace'
       t.scheme = 'Parse-iOS'
       t.configuration = 'Release'
-      t.destination = ["\"platform=iOS Simulator,OS=13.0,name=iPhone XS\"",]
+      t.destinations = ["\"platform=iOS Simulator,OS=13.0,name=iPhone XS\"",]
     end
     result = task.execute
     unless result