EventDispatcher: Rename method unregister_event_types to unregister_event_type (#7445)
EventDispatcher: Rename method unregister_event_types to unregister_event_type (#7445)

* Renamed EventDispatcher method unregister_event_types to unregister_event_type.

* Deprecated method unregister_event_types in EventDispatcher.
rnixx/kivy,rnixx/kivy,akshayaurora/kivy,matham/kivy,matham/kivy,akshayaurora/kivy,rnixx/kivy,akshayaurora/kivy,kivy/kivy,kivy/kivy,matham/kivy,kivy/kivy,matham/kivy