Prevent collections.abc.Sequence warning (#607)

Fixes #606.

Author: adamchainz

HISTORY.rst

@@ -3,6 +3,11 @@
 History
 =======
 
+Pending
+-------
+
+* Prevent ``collections.abc.Sequence`` warning.
+
 3.3.0 (2019-12-10)
 ------------------
 

src/django_mysql/models/lookups.py

@@ -1,5 +1,5 @@
-import collections
 import json
+from collections.abc import Sequence
 
 import django
 from django.db.models import CharField, Lookup, Transform
@@ -123,7 +123,7 @@ def as_sql(self, qn, connection):
 
 class JSONSequencesMixin(object):
     def get_prep_lookup(self):
-        if not isinstance(self.rhs, collections.Sequence):
+        if not isinstance(self.rhs, Sequence):
             raise ValueError(
                 "JSONField's '{}' lookup only works with Sequences".format(
                     self.lookup_name