Add date-local to supported widgets

[Segelzwerg]

This maybe similar to #678.

I like to use the widget date-local in my templates. However, this seems to break the date picker as well as the floating label.

class Form(ModelForm):

    class Meta:
        ....
        widgets = {
            'date': DateInput(attrs={'type': 'date-local'}),
            'due_date': DateInput(attrs={'type': 'date-local'}),
            'delivery_date': DateInput(attrs={'type': 'date'}),
        }

Let me know if more information is required.