Use recursive lambdas instead of recursive functions

[rdong8]

This could be a recursive lambda instead of a recursive function, but we need deducing this from C++23 which is implemented in clang-18. Since Fedora 39 currently only has clang-17, I have no way to test it currently.

learn_asio/src/Timer/3.cc

Line 8 in 508ea6f

auto print(const boost::system::error_code&, boost::asio::steady_timer& t, int& count) -> void {