Drop redundant dependency on iso8601

The iso8601 library is currently used directly by test code only. Also
iso8601.UTC is equivalent to datetime.timezone.utc so can be replaced
by the built-in implementation.

Change-Id: I69529687d1bd4e2dcc28c9be1bcbddf5884f3954

magnum/tests/unit/objects/utils.py

@@ -17,7 +17,6 @@
 
 import datetime
 
-import iso8601
 import netaddr
 from oslo_utils import timeutils
 
@@ -208,7 +207,7 @@ def datetime_or_none(dt):
             # NOTE(danms): Legacy objects from sqlalchemy are stored in UTC,
             # but are returned without a timezone attached.
             # As a transitional aid, assume a tz-naive object is in UTC.
-            return dt.replace(tzinfo=iso8601.UTC)
+            return dt.replace(tzinfo=datetime.timezone.utc)
         else:
             return dt
     raise ValueError(_("A datetime.datetime is required here"))

requirements.txt

@@ -10,7 +10,6 @@ alembic>=0.9.6 # MIT
 cliff!=2.9.0,>=2.8.0 # Apache-2.0
 decorator>=3.4.0 # BSD
 eventlet>=0.28.0 # MIT
-iso8601>=0.1.11 # MIT
 jsonpatch!=1.20,>=1.16 # BSD
 keystoneauth1>=3.14.0 # Apache-2.0
 keystonemiddleware>=9.0.0 # Apache-2.0