pcr: libreboot-utils: fix python dependencies
Without that fix it still builds fine with makepkg but it fails
because python-setuptool is missing:
| Traceback (most recent call last):
| File "/build/libreboot-utils/src/libreboot-20211122_src/coreboot/default/util/me_cleaner/setup.py", line 3, in <module>
| from setuptools import setup
| ModuleNotFoundError: No module named 'setuptools'
| ==> ERROR: A failure occurred in build().
| Aborting...
In addition the 'python' package provides 'python3', but it's probably
more clear if we use the 'python' package as dependency instead of
what it provides.
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>