westoy: Fix the version number we request for wl_seat
westoy: Fix the version number we request for wl_seat

If the compositor supports a lower version, like version 2, we need
to request that instead of version 3.

xorgy/weston,krezovic/weston,Fantu/compositor-spice,sir-murray/weston,kwm81/weston,sir-murray/weston,eyolfson/weston,Fantu/compositor-spice,xorgy/weston,Gnurou/weston,jonnylamb/weston,Fantu/compositor-spice,krezovic/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,giucam/weston,kwm81/weston,Gnurou/weston,udoprog/weston,udoprog/weston,giucam/weston,Tarnyko/weston-xdg_surface_present,mchalupa/weston,jonnylamb/weston,mchalupa/weston