upgrade.rb in httpx-0.22.2

- old
+ new

@@ -33,10 +33,12 @@
       module InstanceMethods
         def fetch_response(request, connections, options)
           response = super
 
           if response
-            return response unless response.respond_to?(:headers) && response.headers.key?("upgrade")
+            return response unless response.is_a?(Response)
+
+            return response unless response.headers.key?("upgrade")
 
             upgrade_protocol = response.headers["upgrade"].split(/ *, */).first
 
             return response unless upgrade_protocol && options.upgrade_handlers.registry.key?(upgrade_protocol)
 