Queue worker daemon should also listen for SIGQUIT

[LachlanArthur]

This PR adds a listener for the SIGQUIT signal.

The queue worker currently listens for SIGTERM to gracefully exit.

However, the official Docker PHP-FPM images (and most images based on them) have the stop signal set to SIGQUIT instead:

$ docker inspect php:8.1-fpm | jq '.[0].ContainerConfig.StopSignal'
> "SIGQUIT"

This means that when Docker executes a stop/restart/etc command, the SIGQUIT signal sent by Docker is not detected. The queue worker continues to run jobs up until it's SIGKILLed by Docker - potentially halfway through a job.