Redshift-gtk creates a new redshift -v instance on each login

[jamaggs]

Describe the bug
I have redshift-gtk as an autostart in xfce with autostart selected. This puts redshift-gtk into my startup applications.

However, every time a log out and log in again, there is an extra version of redshift -v running, so after some time I have one redshift-gtk process and many redshift -v processes running.

• [I have checked the FAQ](https://github.com/jonls/redshift/blob/master/README.md#faq and my issue is not mention there.

To Reproduce
Steps to reproduce the behavior:

1. Install redshift, launch and select autostart
2. Log in and out of xfce a few times
3. Start task manager and see multiple redshift -v processes

Expected behavior
I'd expect that there would only be one redshift -v process

Software versions (please complete the following information):

• OS: Mint 22.1
• Redshift version: 1.12
• Distribution: Mint 22.1
• Redshift installed from: apt

[hartwork]

@jamaggs please see issue #912 🙏