meson: Fix unknown kw argument in gnome.generate_gir
This argument has been removed in Meson 0.61.0:
gck/meson.build:130:2: ERROR: gnome.generate_gir got unknown keyword arguments "packages"https://github.com/mesonbuild/meson/commit/f8fc5cb860465718fe7c79a1bf1fe00659f138de:
The packages argument to gnome.generate_gir was allowed, but never did anything, so stop passing it.