3.0.1

Fixed

• orjson.dumps() raises an exception if the object to be serialized
  is not given as a positional argument. orjson.dumps({}) is intended and ok
  while orjson.dumps(obj={}) is an error. This makes it consistent with the
  documentation, help() annotation, and type annotation.
• Fix orphan reference in exception creation that leaks memory until the
  garbage collector runs.

Changed

• Improve serialization performance marginally by using the fastcall/vectorcall
  calling convention on python3.7 and above.
• Reduce build time.