fix ci for setuptools 72

[lexdene]

setuptools 72.0.0, which released about 7 hours ago, has removed setuptools.command.test module.
ref: pypa/setuptools#4458, pypa/setuptools#4518, pypa/setuptools#4519

So I removed pytest from setup.py, and used a pytest command instead of python setup.py test.

fix:

Traceback (most recent call last):
  File "/home/runner/work/libmc/libmc/setup.py", line 12, in <module>
    from setuptools.command.test import test as TestCommand
ModuleNotFoundError: No module named 'setuptools.command.test'