Add a default value for headers in AsciicastCreator

app/services/asciicast_creator.rb

@@ -1,6 +1,6 @@
 class AsciicastCreator
 
-  def create(attributes, headers)
+  def create(attributes, headers = {})
     attributes = AsciicastParams.new(attributes, headers).to_h
     asciicast = Asciicast.create!(attributes, without_protection: true)
     AsciicastWorker.perform_async(asciicast.id)