Remove unused method from container registry client

lib/container_registry/client.rb

@@ -15,10 +15,6 @@ module ContainerRegistry
       @options = options
     end
 
-    def update_token(token)
-      @options[:token] = token
-    end
-
     def repository_tags(name)
       response_body faraday.get("/v2/#{name}/tags/list")
     end