Build slapos-node using either python3 or python2

See merge request !161
5 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

00:47:20

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

07:56:01

passed SlapOS-Master.StandaloneDeploymentScriptTest-Debian.Buster

09:15:18

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:36:14

failed Wendelin.StandaloneDeploymentScriptTest-Debian.Stretch

15:03:23