add Hash#expire_at.

Author: Mikhail Varabyou

lib/kredis/types/hash.rb

@@ -5,7 +5,7 @@
 class Kredis::Types::Hash < Kredis::Types::Proxying
   prepend Kredis::DefaultValues
 
-  proxying :hget, :hset, :hmget, :hdel, :hgetall, :hkeys, :hvals, :del, :exists?
+  proxying :hget, :hset, :hmget, :hdel, :hgetall, :hkeys, :hvals, :del, :exists?, :expire, :expireat
 
   attr_accessor :typed
 
@@ -47,6 +47,10 @@ def values
     strings_to_types(hvals || [], typed)
   end
 
+  def expire_at(datetime)
+    expireat datetime.to_i
+  end
+
   private
     def set_default
       update(**default)