modules/gnome: ignore the return type of _get_dep
modules/gnome: ignore the return type of _get_dep

This is hard to fix, and it's really doing something bad anyway. But we
know it's right, so just tell mypy to not worry about it.

pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson