Fix conditional that checks if ActiveRecord is < 5.0.2:

- The conditional wasn't correct, any version with a `0` minor and
  `< 2` patch (which is true for 6.0.0) would return that the version
  was `< 5.0.2`.

lib/paper_trail/type_serializers/postgres_array_serializer.rb

@@ -29,8 +29,7 @@ def deserialize(array)
       private
 
       def active_record_pre_502?
-        ::ActiveRecord::VERSION::MAJOR < 5 ||
-          (::ActiveRecord::VERSION::MINOR.zero? && ::ActiveRecord::VERSION::TINY < 2)
+        ::ActiveRecord.version < Gem::Version.new('5.0.2')
       end
 
       def serialize_with_ar(array)