ref(worker): Amend function signature for coroutines

Coroutines have a return value, however the current function signature for the worker methods does not accomodate for this. Therefore, this signature was changed. GH-4578

sentry_sdk/worker.py

@@ -34,7 +34,7 @@ def kill(self) -> None:
  pass
 
  def flush(
- self, timeout: float, callback: Optional[Callable[[int, float], None]] = None
+ self, timeout: float, callback: Optional[Callable[[int, float], Any]] = None
  ) -> None:
  """
  Flush the worker.
@@ -50,7 +50,7 @@ def full(self) -> bool:
  pass
 
  @abstractmethod
- def submit(self, callback: Callable[[], None]) -> bool:
+ def submit(self, callback: Callable[[], Any]) -> bool:
  """
  Schedule a callback to be executed by the worker.
 
@@ -149,7 +149,7 @@ def _wait_flush(self, timeout: float, callback: Optional[Any]) -> None:
  pending = self._queue.qsize() + 1
  logger.error("flush timed out, dropped %s events", pending)
 
- def submit(self, callback: Callable[[], None]) -> bool:
+ def submit(self, callback: Callable[[], Any]) -> bool:
  self._ensure_thread()
  try:
  self._queue.put_nowait(callback)