Don't bother with fire-and-forget WS closure

This introduces more problems than what it solves, since now if the
application wants to exit, it may orphan this and cause a lot of
logspam.

This change now closes the websocket synchronously to avoid leaking
tasks upon exit.

replit_river/websocket_wrapper.py

@@ -28,8 +28,8 @@ async def close(self) -> None:
         async with self.ws_lock:
             if self.ws_state == WsState.OPEN:
                 self.ws_state = WsState.CLOSING
-                task = asyncio.create_task(self.ws.close())
-                task.add_done_callback(
-                    lambda _: logger.debug("old websocket %s closed.", self.ws.id)
-                )
+                try:
+                    await self.ws.close()
+                finally:
+                    logger.debug("old websocket %s closed.", self.ws.id)
                 self.ws_state = WsState.CLOSED