Change the default serializer the library is using for example in auth/serializers.py
from django.contrib.auth import authenticate
from django.utils.translation import gettext_lazy as _
from rest_framework import serializers
class MyAuthTokenSerializer(serializers.Serializer):
    email = serializers.EmailField(label=_("Email"))
    password = serializers.CharField(
        label=_("Password",),
        style={'input_type': 'password'},
        trim_whitespace=False
    )
    def validate(self, attrs):
        email = attrs.get('email')
        password = attrs.get('password')
        if email and password:
            user = authenticate(request=self.context.get('request'),
                                email=email, password=password)
            # The authenticate call simply returns None for is_active=False
            # users. (Assuming the default ModelBackend authentication
            # backend.)
            if not user:
                msg = _('Unable to log in with provided credentials.')
                raise serializers.ValidationError(msg, code='authorization')
        else:
            msg = _('Must include "email" and "password".')
            raise serializers.ValidationError(msg, code='authorization')
        attrs['user'] = user
        return attrs
Override the view for example in auth/views.py
from rest_framework.authtoken import views as auth_views
from rest_framework.compat import coreapi, coreschema
from rest_framework.schemas import ManualSchema
from .serializers import MyAuthTokenSerializer
class MyAuthToken(auth_views.ObtainAuthToken):
    serializer_class = MyAuthTokenSerializer
    if coreapi is not None and coreschema is not None:
        schema = ManualSchema(
            fields=[
                coreapi.Field(
                    name="email",
                    required=True,
                    location='form',
                    schema=coreschema.String(
                        title="Email",
                        description="Valid email for authentication",
                    ),
                ),
                coreapi.Field(
                    name="password",
                    required=True,
                    location='form',
                    schema=coreschema.String(
                        title="Password",
                        description="Valid password for authentication",
                    ),
                ),
            ],
            encoding="application/json",
        )
obtain_auth_token = MyAuthToken.as_view()
Hook up the url for example in auth/urls.py
from .views import obtain_auth_token
urlpatterns = [
    re_path(r'^api-token-auth/', obtain_auth_token),
]
and you are ready to go!!