Remove Cirrus testing

Cirrus is now redundant with tmt. Also, with the recent change, cirrus
would need to be updated and reworked to work with podman-next and
without it.

Also, replace badge in the README

Signed-off-by: Nicola Sella <[email protected]>

Author: inknos

.cirrus.yml

@@ -1,5 +1,5 @@
 # podman-py
-[![Build Status](https://api.cirrus-ci.com/github/containers/podman-py.svg)](https://cirrus-ci.com/github/containers/podman-py/main)
+[![PyPI Latest Version](https://img.shields.io/pypi/v/podman)](https://pypi.org/project/podman/)
 
 This python package is a library of bindings to use the RESTful API of [Podman](https://github.com/containers/podman).
 It is currently under development and contributors are welcome!