🐛 ModelSelect2MultipleWidget fails to unselect from dropdown

[SebastianSeltmann]

Bug Description

The ModelSelect2Multiple Widget cannot correctly remove items from the selection by clicking on them in the dropdown.
The same desired behaviour works correctly in the Select2Multiple Widget.

attrs such as data-minimum-input-length make no difference.

django-select2 v8.4.1

Steps to Reproduce

1. Create a Form with a ModelSelect2MultipleWidget widget, as described in the docs
2. Select one or more things
3. Try to unselect anything (not by hitting backspace, but by clicking on the dropdown)
4. The item remains selected

Expected Behavior

I expected the item to become unselected. The Select2Multiple works like that, and so does vanilla Select2.