fixup: switch type to BaseException for python 3.8 compatibility

strawberry/subscriptions/protocols/graphql_transport_ws/handlers.py

@@ -116,14 +116,18 @@ async def handle_connection_init_timeout(self) -> None:
             self.connection_timed_out = True
             reason = "Connection initialisation timeout"
             await self.close(code=4408, reason=reason)
-        except Exception as error:
+        except BaseException as error:
+            # for python 3.8 compatibility use BaseException
+            # asyncio.CancelledError didn't inherit from Exception in python < 3.9
             await self.handle_task_exception(error)  # pragma: no cover
         finally:
             # do not clear self.connection_init_timeout_task
             # so that unittests can inspect it.
             self.completed_tasks.append(task)
 
-    async def handle_task_exception(self, error: Exception) -> None:
+    async def handle_task_exception(self, error: BaseException) -> None:
+        # for python 3.8 compatibility use BaseException
+        # asyncio.CancelledError didn't inherit from Exception in python < 3.9
         if isinstance(error, asyncio.CancelledError):
             self.task_logger.exception("Worker task cancelled", exc_info=error)
         else: