Fix bug on GTK desktop environments

For some reason this makes the entries on the combo-box huge when covered. It was never bold on windows anyways.

dist/qt_themes/qdarkstyle_midnight_blue/style.qss

@@ -1257,10 +1257,6 @@ QComboBox::item:alternate {
   background: #19232D;
 }
 
-QComboBox::item:checked {
-  font-weight: bold;
-}
-
 QComboBox::item:selected {
   border: 0px solid transparent;
 }