Remove selinux from dependencies

[sugymt]

The selinux module causes some problems if we don't use the system standard python.
Can selinux be removed from molecule-docker dependencies like molecule?

ansible/molecule#3424
ansible/molecule#3388

[conn]

I've also ran into issues with this when running Molecule with pyenv on Rocky 8. Ansible and Molecule seem to run fine with Docker when I hand-patched system_python to use sys.executable instead of selecting a system Python. It also works just fine when I remove the selinux package after installing molecule-plugins.

There's also a fairly recent breaking change to how system_python is selected that upset some folks:
pycontribs/selinux#56

It seems like this library doesn't offer anything but issues. I'd love to see it dropped.

[conn]

PR at #89