setuptools_build_meta: remove python dependency

setuptools_build_meta: remove python dependency

when building additional native python tools that should be used
for additional tasks in python3 package (class-target), the dependency
on target class python creates a dependency loop:

python3-foo-native_1.2.3.bb:do_prepare_recipe_sysroot
python3-pep8-native_1.7.1.bb:do_populate_sysroot
python3-wheel_0.37.1.bb:do_populate_sysroot
python3-bar-native_0.1.2.bb:do_populate_sysroot
python3-pip_22.0.3.bb:do_populate_sysroot
python3-pyflakes-native_2.4.0.bb:do_populate_sysroot
python3_3.10.2.bb:do_populate_sysroot
python3-foo-native_1.2.3_1.2.0.bb:do_fetch
python3-setuptools_59.5.0.bb:do_populate_sysroot

resolve this by removing python3 from DEPENDS.
The correct dependencies are already injected by
setuptools-base class

Signed-off-by: Konrad Weihmann <kweihmann@outlook.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>