Remove dependency on pytz

pytz will be removed from RHEL/CentOS 10 because of the built-in
zoneinfo[1].

Because the current usage of pytz can be very easily replaced, this
removes the dependency on pytz.

[1] https://issues.redhat.com/browse/RHEL-219

Change-Id: Iafcaf2f1095cd7c738dac391a9af10622806e932

ironic_inspector/test/functional.py

@@ -30,7 +30,6 @@ from oslo_config import cfg
 from oslo_config import fixture as config_fixture
 from oslo_utils import timeutils
 from oslo_utils import uuidutils
-import pytz
 import requests
 
 from ironic_inspector.cmd import all as inspector_cmd
@@ -234,7 +233,7 @@ class Base(base.NodeTest):
         # CI Runs in UTC, local machines can fail on the use of the local
         # timezone.
         curr_time = datetime.datetime.fromtimestamp(
-            time.time(), tz=pytz.timezone('UTC'))
+            time.time(), tz=datetime.timezone.utc)
         started_at = timeutils.parse_isotime(status['started_at'])
         self.assertLess(started_at, curr_time)
         if finished:

ironic_inspector/utils.py

@@ -23,7 +23,6 @@ from oslo_config import cfg
 from oslo_log import log
 from oslo_middleware import cors as cors_middleware
 from oslo_middleware import healthcheck as healthcheck_middleware
-import pytz
 import webob
 
 from ironic_inspector.common.i18n import _
@@ -329,7 +328,7 @@ def get_inventory(data, node_info=None):
     return inventory
 
 
-def iso_timestamp(timestamp=None, tz=pytz.timezone('utc')):
+def iso_timestamp(timestamp=None, tz=datetime.timezone.utc):
     """Return an ISO8601-formatted timestamp (tz: UTC) or None.
 
     :param timestamp: such as time.time() or None

requirements.txt

@@ -18,7 +18,6 @@ keystoneauth1>=4.2.0 # Apache-2.0
 keystonemiddleware>=4.18.0 # Apache-2.0
 netaddr>=0.7.18 # BSD
 pbr>=3.1.1 # Apache-2.0
-pytz>=2013.6 # MIT
 PyYAML>=5.3.1
 openstacksdk>=0.40.0 # Apache-2.0
 oslo.concurrency>=3.26.0 # Apache-2.0