Remove deprecated extra gui_qt from setup.cfg (#1704)

Author: user202729

setup.cfg

@@ -64,7 +64,7 @@ plover.dictionary =
 	rtf  = plover.dictionary.rtfcre_dict:RtfDictionary
 plover.gui =
 	none = plover.gui_none.main
-	qt   = plover.gui_qt.main [gui_qt]
+	qt   = plover.gui_qt.main
 plover.gui.qt.machine_option =
 	plover.machine.base:SerialStenotypeBase = plover.gui_qt.machine_options:SerialOption
 	plover.machine.keyboard:Keyboard        = plover.gui_qt.machine_options:KeyboardOption