[IMPROVEMENT] "Check for updates" grayed out

[MikaelKW]

Please confirm these before moving forward.

• I have searched for my feature proposal and have not found a work-in-progress/duplicate/resolved/discarded issue.
• This improvement refers to an existing feature. If you want to suggest a new feature, please use this template.
• This improvement is not a bug. If you want to report a bug, please use this template.

Describe the improvement

The button "Check for updates" under the page "General preferances" becomes greyed out if you unmark "Update UniGetUI automatically". Would be great if it was still possible to check for a new version of UniGetUI without having to turn on automatic updating of the application.

Describe how this improvement could help users

For those that do not wish to have automatic updates turned on, but still want to have the ability to check for a new version inside the application.

[redactedscribe]

I agree with this being an improvement. No automatic updates, but the ability to manually check for one.