fix: properly handle CancelledError in switch accept loop (#1537)

Signed-off-by: MorganaFuture <andrewmochalskyi@gmail.com>

Author: MorganaFuture

libp2p/switch.nim

@@ -273,6 +273,9 @@ proc accept(s: Switch, transport: Transport) {.async: (raises: []).} =
       conn =
         try:
           await transport.accept()
+        except CancelledError as exc:
+          slot.release()
+          raise exc
         except CatchableError as exc:
           slot.release()
           raise