Rename `Gitlab::Serialize` module to reuse it later

app/models/ci/build.rb

@@ -19,7 +19,7 @@ module Ci
     end
 
     serialize :options
-    serialize :yaml_variables, Gitlab::Serialize::Ci::Variables
+    serialize :yaml_variables, Gitlab::Serializer::Ci::Variables
 
     validates :coverage, numericality: true, allow_blank: true
     validates_presence_of :ref

lib/gitlab/serialize/ci/variables.rb → lib/gitlab/serializer/ci/variables.rb

 module Gitlab
-  module Serialize
+  module Serializer
     module Ci
       # This serializer could make sure our YAML variables' keys and values
       # are always strings. This is more for legacy build data because

spec/lib/gitlab/serialize/ci/variables_spec.rb → spec/lib/gitlab/serializer/ci/variables_spec.rb

 require 'spec_helper'
 
-describe Gitlab::Serialize::Ci::Variables do
+describe Gitlab::Serializer::Ci::Variables do
   subject do
     described_class.load(described_class.dump(object))
   end