Fix tests for django-filter 1.0.0

Fixes openwisp#120.

README.rst

@@ -429,10 +429,6 @@ Example result response (cut to one element only instead of 10):
 Filters
 -------
 
-**note**: this feature is compatible with django-filter up to version 0.15.
-If you need compatibility with version django-filter 1.0 please send a patch
-(see `issue #120 <https://github.com/djangonauts/django-rest-framework-gis/issues/120>`_).
-
 We provide a ``GeometryFilter`` field as well as a ``GeoFilterSet``
 for usage with ``django_filter``. You simply provide, in the query
 string, one of the textual types supported by ``GEOSGeometry``. By
@@ -446,8 +442,8 @@ GeometryFilter
     from rest_framework_gis.filterset import GeoFilterSet
 
     class RegionFilter(GeoFilterSet):
-        slug = filters.CharFilter(name='slug', lookup_type='istartswith')
-        contains_geom = filters.GeometryFilter(name='geom', lookup_type='contains')
+        slug = filters.CharFilter(name='slug', lookup_expr='istartswith')
+        contains_geom = filters.GeometryFilter(name='geom', lookup_expr='contains')
 
         class Meta:
             model = Region

requirements-test.txt

@@ -2,5 +2,5 @@ psycopg2
 djangorestframework>=3.3
 coverage==3.7.1  # rq.filter: >=3,<4
 coveralls
-django-filter>=0.15,<1.0
+django-filter
 contexttimer

tests/django_restframework_gis_tests/views.py

@@ -132,10 +132,12 @@ class GeojsonLocationNoIdDetails(generics.RetrieveUpdateDestroyAPIView):
 
 
 class LocationFilter(GeoFilterSet):
-    contains_properly = GeometryFilter(name='geometry', lookup_type='contains_properly')
+    contains_properly = GeometryFilter(name='geometry',
+                                       lookup_expr='contains_properly')
 
     class Meta:
         model = Location
+        fields = ['contains_properly']
 
 class GeojsonLocationContainedInGeometry(generics.ListAPIView):
     queryset = Location.objects.all()