Disable auto discovery

Tripleo-ci jobs are broken after latest release of setuptools 61.0
because of breaking changes which are not backwork compatible,
details in related bug and [1].

Users that don't set ``packages``, ``py_modules``, or ``configuration`` are
still likely to observe the auto-discovery behavior, which may halt the
build if the project contains multiple directories and/or multiple Python
files directly under the project root.

To disable auto discovery, one can do below in setup.py

~~~
setuptools.setup(..,packages=[],..)
~~~

or

~~~
setuptools.setup(..,py_modules=[],..)
~~~

Also, adding ^setup.*$ under irrelevant-files as content-provider
parent[2] also have same.

[1] https://github.com/pypa/setuptools/issues/3197
[2] https://opendev.org/openstack/tripleo-ci/src/branch/master/zuul.d/base-upstream.yaml#L92

Change-Id: I850cb7312e34a42d049b70030c4f0609d82ec54f
Releated-Bug: #1966382

setup.py

@@ -16,4 +16,5 @@ import setuptools
 
 setuptools.setup(
     setup_requires=['pbr'],
+    py_modules=[],
     pbr=True)