Fix utcfromtimestamp() deprecation warning (#424)

Author: kbaikov

CHANGELOG.rst

@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* Fix ``utcfromtimestamp()`` warning on Python 3.12+.
+
+  Thanks to Konstantin Baikov in `PR #424 <https://github.com/adamchainz/time-machine/pull/424>`__.
+
 * Avoid calling deprecated ``uuid._load_system_functions()`` on Python 3.9+.
 
   Thanks to Nikita Sobolev for the ping in `CPython Issue #113308 <https://github.com/python/cpython/issues/113308>`__.

src/time_machine/__init__.py

@@ -350,7 +350,7 @@ def utcnow() -> dt.datetime:
     if not coordinates_stack:
         result: dt.datetime = _time_machine.original_utcnow()
         return result
-    return dt.datetime.utcfromtimestamp(time())
+    return dt.datetime.fromtimestamp(time(), dt.timezone.utc).replace(tzinfo=None)
 
 
 # time module