Clang CI builds fail due to linker error

Clang 17 and 18 CI builds fail due to a Qt related linker error:

/usr/bin/ld: ui/libplug-ui.a(mainwindow.cpp.o): in function `QString::toStdString() const':
/usr/include/x86_64-linux-gnu/qt6/QtCore/qstring.h:1477:(.text._ZNK7QString11toStdStringEv[_ZNK7QString11toStdStringEv]+0x12e): undefined reference to `QByteArray::toStdString() const'
clang++-18: error: linker command failed with exit code 1 (use -v to see invocation)