x11/gnome-session: unbreak build with Meson 0.61.0
data/meson.build:60:2: ERROR: Function does not take positional arguments.
data/meson.build:91:2: ERROR: Function does not take positional arguments.
PR: 260943
Regressed by: https://github.com/mesonbuild/meson/commit/61f2866a9fa1