Remove fallback to pytz

The zoneinfo module is available in Python >= 3.9 . Now the minimum
supported version is 3.9 and we can assume it's always available.

Change-Id: Ibfa416da3edb45403e10e2060131717d36cffc46

heat/engine/constraint/common_constraints.py

@@ -14,13 +14,7 @@
 import croniter
 import eventlet
 import netaddr
-
-try:
-    import zoneinfo
-except ImportError:
-    # zoneinfo is available in Python >= 3.9
-    import pytz
-    zoneinfo = None
+import zoneinfo
 
 from neutron_lib.api import validators
 from oslo_utils import timeutils
@@ -173,10 +167,7 @@ class TimezoneConstraint(constraints.BaseCustomConstraint):
         if not value:
             return True
         try:
-            if zoneinfo:
-                zoneinfo.ZoneInfo(value)
-            else:
-                pytz.timezone(value)
+            zoneinfo.ZoneInfo(value)
             return True
         except Exception as ex:
             self._error_message = _(

heat/tests/clients/test_swift_client.py

@@ -13,13 +13,7 @@
 
 import datetime
 from unittest import mock
-
-try:
-    import zoneinfo
-except ImportError:
-    # zoneinfo is available in Python >= 3.9
-    import pytz
-    zoneinfo = None
+import zoneinfo
 
 from testtools import matchers
 
@@ -132,10 +126,7 @@ class SwiftUtilsTest(SwiftClientPluginTestCase):
 
     def test_parse_last_modified(self):
         self.assertIsNone(self.swift_plugin.parse_last_modified(None))
-        if zoneinfo:
-            tz = zoneinfo.ZoneInfo('GMT')
-        else:
-            tz = pytz.timezone('GMT')
+        tz = zoneinfo.ZoneInfo('GMT')
         now = datetime.datetime(
             2015, 2, 5, 1, 4, 40, 0, tz)
         now_naive = datetime.datetime(

requirements.txt

@@ -50,7 +50,6 @@ python-troveclient>=2.2.0 # Apache-2.0
 python-vitrageclient>=2.7.0 # Apache-2.0
 python-zaqarclient>=1.3.0 # Apache-2.0
 python-zunclient>=3.4.0 # Apache-2.0
-pytz>=2013.6;python_version<"3.9" # MIT
 PyYAML>=5.1 # MIT
 requests>=2.23.0 # Apache-2.0
 tenacity>=6.1.0 # Apache-2.0