fix: explicitly require CGI

Closes #49

lib/http/cookie.rb

@@ -6,6 +6,7 @@ require 'time'
 require 'uri'
 require 'domain_name'
 require 'http/cookie/ruby_compat'
+require 'cgi'
 
 module HTTP
   autoload :CookieJar, 'http/cookie_jar'

lib/http/cookie_jar/mozilla_store.rb

@@ -400,8 +400,6 @@ class HTTP::CookieJar
         }
       end
     else
-      require 'cgi'
-
       def encode_www_form(enum)
         enum.map { |k, v| "#{CGI.escape(k)}=#{CGI.escape(v)}" }.join('&')
       end