Added perl-XML-XPath dependency

yast2-wagon does not build correctly because of this missing dependency in yast2:

```
Can't locate XML/XPath.pm
BEGIN failed--compilation aborted at /usr/share/YaST2/modules/RegistrationStatus.pm line 27.
```

See https://build.opensuse.org/package/live_build_log?arch=x86_64&package=yast2-wagon&project=YaST%3AHead&repository=openSUSE_Factory