Feature Request: Gotify support

[amau05]

User stories

• As a User it would be really convenient to me if I could use my existing Gotify installation to get a notification when Cupdate flag a new update.

Feature description

Adding a way to send changes to a Gotify server so it could send a notification to it's paired devices.

Thanks for the work it's seems great, I'm using the Portainer CE so I don't get notified when there is new updates, this helps a lot to keep track of my too many containers.

Small detail but the docker compose install the previous version of the app so my first container flagged was yours ;D . I fixed it for myself of course but others might not.

[AlexGustafsson]

Thanks for the request and checking the install docs! The docs are now updated to refer to the latest release again.