Fix compilation with boost >= 1.86

[Chocobo1]

No description provided.

[milahu]

Fix compilation with boost >= 1.86

no, this breaks with boost 1.87

src/main.cpp:68:20: error: 'io_service' has not been declared in 'boost::asio'
   68 | using boost::asio::io_service;
      |                    ^~~~~~~~~~

see also #52