update timeutils usage to work with celery 4

djcelery/backends/database.py

@@ -2,6 +2,7 @@
 
 from celery import current_app
 from celery.backends.base import BaseDictBackend
+
 try:
     from celery.utils.timeutils import maybe_timedelta
 except ImportError:

djcelery/schedulers.py

@@ -10,7 +10,11 @@
 from celery.beat import Scheduler, ScheduleEntry
 from celery.utils.encoding import safe_str, safe_repr
 from celery.utils.log import get_logger
-from celery.utils.timeutils import is_naive
+
+try:
+    from celery.utils.timeutils import is_naive
+except ImportError:
+    from celery.utils.time import is_naive
 
 from django.db import transaction
 from django.core.exceptions import ObjectDoesNotExist

djcelery/snapshot.py

@@ -10,7 +10,11 @@
 from celery.events.snapshot import Polaroid
 from celery.five import monotonic
 from celery.utils.log import get_logger
-from celery.utils.timeutils import maybe_iso8601
+
+try:
+    from celery.utils.timeutils import maybe_iso8601
+except ImportError:
+    from celery.utils.time import maybe_iso8601
 
 from .models import WorkerState, TaskState
 from .utils import fromtimestamp, correct_awareness