fix: Puma does not support SIGQUIT but use SIGTERM the default kill signal

[rrondeau]

Hi

Every restart of my instance produced a core dump since last year.

stopped: puma (terminated by SIGQUIT (core dumped))

I tracked down the issue to puma supervisord config, the stop signal is overrided, a leftover from unicorn config i think ;-)
Puma documentation for supported signals : https://github.com/puma/puma/blob/main/docs/signals.md#puma-signals

If you need anything done to the PR, feel free to ask.

Thanks
Raphaël