add Rack deps introduced by Mock classes

`No type error detected. 🧉`

Author: ParadoxV5

gems/rack/2.2.2/_test/Steepfile

@@ -4,6 +4,8 @@ target :test do
 
   repo_path "../../../"
   library "rack"
+  library "cgi"
+  library "uri"
 
   configure_code_diagnostics(D::Ruby.all_error)
 end