Support ubuntu-20

[v1v]

What

Enable Ubuntu 20 in test-kitchens

Issues

• Wait for Add Ubuntu 20.04 to CI and ansible-test ansible/ansible#69161
• Causes lowercase the instance-name test-kitchen/kitchen-docker#375

Issues with the test-kitchen

✅ solved now

11:14:30        docker: invalid reference format: repository name must be lowercase.
11:14:30        See 'docker run --help'.
11:14:30 >>>>>> ------Exception-------
11:14:30 >>>>>> Class: Kitchen::ActionFailed
11:14:30 >>>>>> Message: 1 actions failed.
11:14:30 >>>>>>     Failed to complete #create action: [Expected process to exit with [0], but received '125'
11:14:30 ---- Begin output of docker -H unix:///var/run/docker.sock run -d -p 22 --name ossubuntu2004-nologin-devopsciimmutableubun-taklg9ok --privileged PyYAML /usr/sbin/sshd -D -o UseDNS=no -o UsePAM=no -o PasswordAuthentication=yes -o UsePrivilegeSeparation=no -o PidFile=/tmp/sshd.pid ----
11:14:30 STDOUT: 
11:14:30 STDERR: docker: invalid reference format: repository name must be lowercase.
11:14:30 See 'docker run --help'.
11:14:30 ---- End output of docker -H unix:///var/run/docker.sock run -d -p 22 --name ossubuntu2004-nologin-devopsciimmutableubun-taklg9ok --privileged PyYAML /usr/sbin/sshd -D -o UseDNS=no -o UsePAM=no -o PasswordAuthentication=yes -o UsePrivilegeSeparation=no -o PidFile=/tmp/sshd.pid ----
11:14:30 Ran docker -H unix:///var/run/docker.sock run -d -p 22 --name ossubuntu2004-nologin-devopsciimmutableubun-taklg9ok --privileged PyYAML /usr/sbin/sshd -D -o UseDNS=no -o UsePAM=no -o PasswordAuthentication=yes -o UsePrivilegeSeparation=no -o PidFile=/tmp/sshd.pid returned 125] on oss-ubuntu-2004

I managed to bypass it locally by setting the hostname/computer-name to something else (lowercase)

[jmlrt]

jenkins test this please

[jmlrt]

LGTM⛴