update package and fix build

[acxz]

resolves #9

[acxz]

Note: This introduces python2 but fixes the build.

[bionade24]

Looking into it, don't like the python2 deps. We probably kicked them out at some qt package.

[acxz]

I don't like them either, but I hate people not using ROS on Arch more. We can try to resolve the issue while the package still works, instead of have Arch users wait for us.

[jwhendy]

See my latest comment on #9 for my analysis. tl;dr: I think we have a python3 compatible way forward that does not require bringing back python2 deps.

[bionade24]

Thanks @jwhendy for the research. I now patched ros-melodic-qt-binding, so problems should be solved soon.