update dependencies and upgrade code for django where needed/possible

src/c3nav/mapdata/models/geometry/base.py

@@ -3,7 +3,7 @@ from contextlib import contextmanager
 
 from django.db import models
 from django.utils.functional import cached_property
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from shapely.geometry import Point, box
 from shapely.ops import unary_union
 

src/c3nav/mapdata/models/geometry/level.py

@@ -10,7 +10,7 @@ from django.db import models
 from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.text import format_lazy
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from scipy.sparse.csgraph._shortest_path import dijkstra
 from shapely import prepared
 from shapely.affinity import scale

src/c3nav/mapdata/models/geometry/space.py

@@ -7,7 +7,7 @@ from django.db import models
 from django.urls import reverse
 from django.utils.functional import cached_property
 from django.utils.text import format_lazy
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from shapely.geometry import CAP_STYLE, JOIN_STYLE, mapping
 
 from c3nav.mapdata.fields import GeometryField, I18nField, JSONField