Python: Fix "implicit namespace packages" migration

... by omitting `__init__.py` from `crate` namespace package altogether,
see "PEP 420" [1] and "Package Discovery and Namespace Package » Finding
namespace packages" [2].

[1] https://peps.python.org/pep-0420/
[2] https://setuptools.pypa.io/en/latest/userguide/package_discovery.html#namespace-packages

Author: amotl

setup.py

@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 
 import functools
-from setuptools import setup
+from setuptools import find_namespace_packages, setup
 
 
 def read(filename):
@@ -26,8 +26,8 @@ def read(filename):
     entry_points={
         'console_scripts': []
     },
+    packages=find_namespace_packages('src'),
     package_dir={'': 'src'},
-    packages=['crate.qa'],
     install_requires=[
         'crate>=1.0.0.dev2',
         'cr8>=0.25.0',