prepare 8.2.1 release (#229)

## [8.2.1] - 2023-10-20
### Fixed:
- Replace deprecated `utcfromtimestamp` usage.

---------

Co-authored-by: Robert J. Neal <[email protected]>
Co-authored-by: Robert J. Neal <[email protected]>
Co-authored-by: LaunchDarklyCI <[email protected]>
Co-authored-by: Eli Bishop <[email protected]>
Co-authored-by: Ben Woskow <[email protected]>
Co-authored-by: Ember Stevens <[email protected]>
Co-authored-by: ember-stevens <[email protected]>
Co-authored-by: Matthew M. Keeler <[email protected]>
Co-authored-by: charukiewicz <[email protected]>
Co-authored-by: LaunchDarklyReleaseBot <[email protected]>
Co-authored-by: Christian Charukiewicz <[email protected]>
Co-authored-by: Matthew M. Keeler <[email protected]>
Co-authored-by: Ben Woskow <[email protected]>
Co-authored-by: Gavin Whelan <[email protected]>
Co-authored-by: Elliot <[email protected]>
Co-authored-by: Gabor Angeli <[email protected]>
Co-authored-by: Elliot <[email protected]>
Co-authored-by: LaunchDarklyCI <[email protected]>
Co-authored-by: hroederld <[email protected]>
Co-authored-by: Louis Chan <[email protected]>
Co-authored-by: prpnmac <[email protected]>
Co-authored-by: Louis Chan <[email protected]>
Co-authored-by: Daniel Fritz <[email protected]>

Author: 16 people

ldclient/impl/model/value_parsing.py

@@ -1,16 +1,16 @@
 import re
 from re import Pattern
 from semver import VersionInfo
-from datetime import tzinfo, timedelta, datetime
+from datetime import tzinfo, timedelta, datetime, timezone
 from numbers import Number
 from typing import Any, Optional
 
 import pyrfc3339
 
 _ZERO = timedelta(0)
 
-# A UTC class.
 
+# A UTC class.
 class _UTC(tzinfo):
     """UTC"""
 
@@ -23,7 +23,8 @@ def tzname(self, dt):
     def dst(self, dt):
         return _ZERO
 
-_epoch = datetime.utcfromtimestamp(0).replace(tzinfo=_UTC())
+
+_epoch = datetime.fromtimestamp(0, timezone.utc)
 
 
 def is_number(input: Any) -> bool: