graphics/gimp3-app: add devel/apstream to LIB_DEPENDS (+)

On some systems with missed devel/appsteam from installed, gimp3 app claims missed library

ld-elf.so.1: Shared object "libappstream.so.5" not found, required by "gimp"

Declare devel/apsstream not as only build dependency but also add as LIB_DEPENDS

PR: 291058