python3-pygobject: remove python3-setuptools from RDEPENDS

python3-pygobject: remove python3-setuptools from RDEPENDS

python3-setuptools is an optional build-dependency of pygobject but
it is not necessary to run it, as also documented by the upstream
packaging guide:

https://gitlab.gnome.org/GNOME/pygobject/blob/master/docs/packagingguide.rst

Remove it from RDEPENDS to shrink the runtime dependency chain, as
setuptools includes scripts to download other packages, which might not
be desired on a minimal image.

Signed-off-by: Luca Boccassi <luca.boccassi@microsoft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>