The only reason that librsvg depends python is /usr/bin/rsvg, which is an old script that's deprecated in favor of /usr/bin/rsvg-convert. I suggest removing the dependency, or separating it into a "deprecated" flag, or similar.
Not sure if other packages are still relying in /usr/bin/rsvg :-/
librsvg-2.36.0 no longer installs /usr/bin/rsvg per upstream decision, and therefore no longer depends on python.