Use to_liquid_value in uniq filter (#1948)

* Use to_liquid_value in uniq filter

* Bump version to 5.8.4

lib/liquid/standardfilters.rb

@@ -1081,7 +1081,10 @@ module Liquid
       end
 
       def uniq(&block)
-        to_a.uniq(&block)
+        to_a.uniq do |item|
+          item = Utils.to_liquid_value(item)
+          block ? yield(item) : item
+        end
       end
 
       def compact

lib/liquid/version.rb

@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.8.3"
+  VERSION = "5.8.4"
 end