Fix active_relation_resource_finder.rb

I think there was a little mistake in here, your probably meant
`context = options[:context]` instead of `context = context`
This solve an issue I had while fetching relationships

Author: Clement Berti

lib/jsonapi/active_relation_resource_finder.rb

@@ -131,7 +131,7 @@ def count_related(source_rid, relationship_name, options = {})
         relationship = _relationship(relationship_name)
         related_klass = relationship.resource_klass
 
-        context = context
+        context = options[:context]
 
         records = records(context: context)
         records, table_alias = apply_join(records, relationship, options)