fix: ModuleNotFoundError: No module named 'utils'

[milahu]

error was

$ python3 -c "import btdht"
...
  File "/nix/store/vl11kw645rjqd46irlsw2bkch24p9p0i-python3.12-btdht-0.3.3/lib/python3.12/site-packages/btdht/__init__.py", line 13, in <module>
    from btdht.dht import  DHT, DHT_BASE, Node, Bucket, RoutingTable
  File "btdht/dht.pyx", line 1, in init btdht.dht
  File "btdht/krcp.pyx", line 22, in init btdht.krcp
ModuleNotFoundError: No module named 'utils'