setup: Drop obsolete zip_safe flag

More info in the documentation:
https://setuptools.pypa.io/en/latest/deprecated/zip_safe.html

And fix style by the way.

setup.cfg

@@ -16,7 +16,6 @@ classifiers =
 	Programming Language :: Python :: 3
 
 [options]
-zip_safe = true
 include_package_data = true
 packages = kconfig_hardened_check
 setup_requires = setuptools