Use raspiBackup version info instead of properties file for -U -S update

[framps]

As of now there exist following ways to update raspiBackup.sh:

• Option -U
• Options -U -S

As of now the local version is checked against the remote version in the properties file. Therefore it's not possible to publish a new release without notifying all raspiBackup users of the update and have a silent relase update. (See #899).

Update raspiBackup so option -U will still use the remote properties file but -U -S should use the version from remote raspiBackup to compare with the local raspiBackup version.

[github-actions]

This issue is considered stale now and will be closed in 1 week if there is no activity any more