Remove unused lines

ldvspec/lofardata/models.py

 from django.db import models
-from django_filters import rest_framework as filters
 from urllib.parse import urlsplit
 from django.contrib.auth.models import User
 from django.contrib.postgres.fields import ArrayField
 from celery.result import AsyncResult
-from ldvspec.celery import app as spec_app
 
 
 class DataLocation(models.Model):