fixed: build against QT 6.8

[akva2]

/home/akva/kode/opm/ResInsight/ApplicationLibCode/Application/Tools/RiaTextStringTools.cpp:212:22: error: redefinition of ‘std::strong_ordering operator<=>(const QString&, const QString&)’
  212 | std::strong_ordering operator<=>( const QString& lhs, const QString& rhs )
      |                      ^~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/qt6/QtCore/qglobal.h:63,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qregularexpression.h:9,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/QRegularExpression:1,
                 from /home/akva/kode/opm/ResInsight/ApplicationLibCode/Application/Tools/RiaTextStringTools.h:21,
                 from /home/akva/kode/opm/ResInsight/ApplicationLibCode/Application/Tools/RiaTextStringTools.cpp:19:
/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:777:5: note: ‘std::strong_ordering operator<=>(const QString&, const QString&)’ previously defined here
  777 |     Q_DECLARE_STRONGLY_ORDERED(QString)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~
[1192/2818] Building CXX object ApplicationLibCode/CMakeFiles/ApplicationLibCode.dir/Application/RiaPreferences.cpp.o
ninja: build stopped: subcommand failed.

I'm not entirely sure this was introduced in 6.8 but something like this is needed.

[akva2]

i can't see how the python linting failure is caused by the changes so I will just ignore.

[magnesj]

We are currently using 6.6, as we have seen issues with 6.7 related to theming. We will investigate newer Qt 6 versions after the release of 2024.12.

[magnesj]

https://doc.qt.io/qt-6/qt.html#compareThreeWay-7

[magnesj]

Thanks for the contribution