Debian Unstable repo for the amd64 archicture seems to be stuck on version 13.18 for some reason (only this one; testing, stable etc. all have 13.21 available).
As this is evidently a OBS bug (the package builds fine) and there is nothing I can do about it, please report it to openSUSE. There is a "Report issue" link on the page in your link that should lead to the appropriate issue tracker.
Debian Unstable repo for the amd64 archicture seems to be stuck on version 13.18 for some reason (only this one; testing, stable etc. all have 13.21 available).
https://download.opensuse.org/repositories/home:/tumic:/GPXSee/Debian_Unstable/amd64/