Replace All initializers with dry-structs, remove callable and optional modules and hacks around instanciating, ruby 3 support works now

lib/yookassa.rb

@@ -1,16 +1,13 @@
 # frozen_string_literal: true
 
 require "http"
-require "dry-initializer"
+require "dry-struct"
 require "yookassa/version"
 require "yookassa/payment"
 require "yookassa/refund"
-require "yookassa/response"
-require "yookassa/callable"
-require "yookassa/optional"
 require "yookassa/entity/payment"
 require "yookassa/entity/refund"
-require "yookassa/error"
+require "yookassa/entity/error"
 require "yookassa/config"
 require "yookassa/http_helpers"