podman: install "rich" dependency

This dependency was added to podman-py in version 4.8.0, but not added
properly to their requirements. Install it explicitly for our tox
and integration testing as a workaround.

[0] containers/podman-py#350

Change-Id: Ic0d9b2c26fe5474f579b72d6779243b7ad39b420

tests/playbooks/pre.yml

@@ -47,7 +47,7 @@
       when: container_engine == "docker"
 
     - name: Install podman python library
-      command: "{{ virtualenv_path }}/bin/python -m pip install podman"
+      command: "{{ virtualenv_path }}/bin/python -m pip install podman rich"
       when: container_engine == "podman"
 
     - name: Configure Docker repo for Debian/Ubuntu