v8.0.0a1 (Wallaby)

• fix Docker installation
• when creating a configuration template, use a fixed version of kolla-ansible (so that templates are not affected when future versions of Enos update the default version of kolla-ansible)
• add support for kolla-ansible 12 (Openstack Wallaby), which is now the default
• add support for Debian 11 base image
• add support for Python 3.10 and 3.11
• drop support for Python 3.7