Add support for upcoming Boost 1.87.0 (Boost.Asio removals)
Advance notice that Monero does not compile with upcoming Boost 1.87.0 (based on beta1) as Boost.Asio has removed the deprecated io_service https://github.com/boostorg/asio/commit/ec0908c562102915423d8bd7aefd3079efbb6c86

This causes errors like:
```
contrib/epee/include/net/net_utils_base.h:33:10: fatal error: 'boost/asio/io_service.hpp' file not found
   33 | #include <boost/asio/io_service.hpp>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
```

And impacts all usage of `boost::asio::io_service` (along with various other removed functions/methods)

io_service was deprecated in favor of io_context back in 1.66.0 (https://github.com/boostorg/asio/commit/b60e92b13ef68dfbb9af180d76eae41d22e19356). Easiest approach is to require a minimum of Boost 1.66.0 and use newer APIs. Otherwise, would need to create many `#if BOOST_VERSION ...` conditions for compatibility.

Related: https://www.boost.org/doc/libs/1_86_0/doc/html/boost_asio/net_ts.html