forms.py

class ListTextWidget(forms.TextInput):
    def __init__(self, data_list, name, *args, **kwargs):
        super(ListTextWidget, self).__init__(*args, **kwargs)
        self._name = name
        self._list = data_list
        self.attrs.update({'list': 'list__{}'.format(self._name)})

    def render(self, name, value, attrs=None):
        text_html = super(ListTextWidget, self).render(name, value, attrs=attrs)
        data_list = '<datalist id="list__{}">'.format(self._name)
        for item in self._list:
            data_list += '<option value="{}">{}</option>'.format(item[0], item[1])
        data_list += '</datalist>'

        return text_html + data_list
        
# Usage
from django import models


class Address(models.Model):
    NSW = 'NSW
    VIC = 'VIC'
    QLD = 'QLD'
    SA = 'SA'
    WA = 'WA'
    TAS = 'TAS'
    NT = 'NT'
    
    STATES = (
        (NSW, 'New South Wales'),
        (VIC, 'Victoria'),
        (QLD, 'Queensland'),
        (SA, 'South Australia'),
        (WA, 'Western Australia'),
        (TAS, 'Tasmania'),
        (NT, 'Northern Territory')
    )


from django import forms    

class ExampleForm(forms.ModelForm):
    class Meta:
        model = Address
        exclude = ['']
        widgets = {
            'state': ListTextWidget(data_list=STATES, name='state_list')
        }

update your code
def render(self, name, value, attrs=None): to def render(self, name, value, attrs=None, renderer=None):