fix version reporting of cli leapp-tool 

version reporting does not seem to work 

```
[root@vmindru-test-03 ~]# /opt/leapp/bin/leapp-tool -v
usage: leapp-tool [-h] [-v]
                  {list-machines,migrate-machine,destroy-containers} ...
leapp-tool: error: too few arguments
[root@vmindru-test-03 ~]# 
```