fix test after making top_level_links class variable

Author: syphax-bouazzouni

lib/ontologies_api_client/collection.rb

@@ -37,7 +37,7 @@ def top_level_links(link = LinkedData::Client.settings.rest_url)
         # Return a link given an object (with links) and a media type
         def uri_from_context(object, media_type)
           object.links.each do |type, link|
-            return link if link.media_type && link.media_type.downcase.eql?(media_type.downcase)
+            return link.dup if link.media_type && link.media_type.downcase.eql?(media_type.downcase)
           end
         end