[Bug Report] multiprocess.py registers a SIGQUIT handler but do nothing.

[liaol]

In the file

uvicorn/uvicorn/supervisors/multiprocess.py

Line 19 in 918dae6

for x in "INT TERM BREAK HUP QUIT TTIN TTOU USR1 USR2 WINCH".split()

a SIGQUIT signal handler is registered.
However, there is no corresponding handle_quit function defined.

As a result, sending a SIGQUIT signal to the main process has no effect.

Perhaps we should remove QUIT from the list of handled signals in the aforementioned line.