setup.cfg: remove zip_safe

The setuptools docs say it's obsolete and no longer needed:
https://setuptools.pypa.io/en/latest/deprecated/zip_safe.html#understanding-the-zip-safe-flag

Author: bluetech

setup.cfg

@@ -46,7 +46,6 @@ package_dir =
 setup_requires =
     setuptools
     setuptools-scm>=6.0
-zip_safe = no
 
 [options.entry_points]
 console_scripts =