Using double splat operator (#5859)

app/lib/ostatus/activity/base.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class OStatus::Activity::Base
-  def initialize(xml, account = nil, options = {})
+  def initialize(xml, account = nil, **options)
     @xml     = xml
     @account = account
     @options = options

app/lib/ostatus/atom_serializer.rb

@@ -319,7 +319,7 @@ class OStatus::AtomSerializer
 
   private
 
-  def append_element(parent, name, content = nil, attributes = {})
+  def append_element(parent, name, content = nil, **attributes)
     element = Ox::Element.new(name)
     attributes.each { |k, v| element[k] = sanitize_str(v) }
     element << sanitize_str(content) unless content.nil?