tty: remove unnecessary semi-colon

[aloisklink]

There's an unneeded semi-colon after the definition of tty_handle::mode_memo_handler() that may cause a compiler to print a warning:

GNU C++ compiler

This no longer seems to appear on newer G++ compilers, only older ones (like GCC-10).

In file included from /home/runner/work/uvw/uvw/src/uvw/tty.h:143,
                 from /home/runner/work/uvw/uvw/src/uvw.hpp:24,
                 from /home/runner/work/uvw/uvw/test/main.cpp:5:
/home/runner/work/uvw/uvw/src/uvw/tty.cpp:25:2: error: extra ‘;’ [-Werror=pedantic]
   25 | };

Logs taken from https://github.com/aloisklink/uvw/actions/runs/5952382537/job/16144246200

Clang

/home/runner/work/uvw/uvw/src/uvw/tty.cpp:25:2: error: extra ';' outside of a function is incompatible with C++98 [-Werror,-Wc++98-compat-extra-semi]
};