Migrate xsane gimp plugin to GIMP 3

Hi,

Fedora started to use GIMP 3 with Fedora 41, so XSANE plugin for GIMP stopped working, because it is written for GIMP 2.

It would be great if XSANE plugin was migrated to GIMP 3 library in the future, so I'm creating the issue to track it.

Thank you in advance!