Remove unreachable None check in _ratelimit_wait

The thread has always finished by the time join() returns, and
outcome.capture never raises, so callback_outcome is never None.

Author: RazerM

src/spacetrack/base.py

@@ -793,8 +793,7 @@ def run_callback():
         t.join()
         # Match the async client, where a callback exception propagates and
         # aborts the request.
-        if callback_outcome is not None:
-            callback_outcome.unwrap()
+        callback_outcome.unwrap()
 
     def __getattr__(self, attr):
         if attr in self.request_controllers: