Move require 'yaml' to state_file.rb

f788af0c8f moved YAML related code to
state_file.rb but didn't move the require from control_cli.rb to
state_file.rb

lib/puma/control_cli.rb

@@ -1,9 +1,9 @@
 require 'optparse'
 require 'puma/const'
 require 'puma/configuration'
-require 'yaml'
 require 'uri'
 require 'socket'
+
 module Puma
   class ControlCLI
 

lib/puma/state_file.rb

@@ -1,3 +1,5 @@
+require 'yaml'
+
 module Puma
   class StateFile
     def initialize