Implement self-update or update checking system

[cydrobolt]

This should be left as an option. Perhaps scraping the latest ref from GitHub?

[UdoKifferbrehl]

Would love that 😍

[Swiftnesses]

+1

[cydrobolt]

We could build a simple update-checking system by making a simple HTTP request on the front-end using AJAX when an admin loads the admin panel. If the current version is lower than the newest stable version, we can trigger a toast notification to the admin on the page.

However, the update-checking system should be optional and future-proof, should the domain where the "current version" is specified becomes abandoned or compromised in the future.