Allow downgrade from current testing to current stable via internal updater

[phnzb]

Is there already an issue for this request?

• [X] I have checked older issues, open and closed

Platform

All

Describe the enhancement you'd like

Please allow downgrading nzbget from the current testing version to the current stable version via the internal updater.

Right now it is only possible via manual reinstallation, which creates some inconvenience if you used the test version only for a specific fix and after the release you want to stay on the stable version.

Platform: Windows / Linux

Extra information

No response