Use Qt versionless target to allow for Qt5 and Qt6 compatibility.

[antoniovazquezblanco]

Qt 5.15 introduced versionless package detection to allow for Qt 5 & Qt6 compatibility.

https://doc.qt.io/qt-6/cmake-qt5-and-qt6-compatibility.html

[hello-adam]

Thanks! I have not been keeping up on Qt stuff. I'll probably have the time to double check and pull this in next week.

[antoniovazquezblanco]

I have found that the code is not compatible with Qt6...

It may be better to just update to 5.15 while using versionless packaging and in a separate PR lets update to Qt6 compat...

[antoniovazquezblanco]

Closed in favour of https://github.com/Mahlet-Inc/hobbits/pull/165