Avoid use of datetime.utc* methods deprecated in Python 3.12 (#93684)

Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com>

tests/components/stream/common.py

@@ -1,5 +1,4 @@
 """Collection of test helpers."""
-from datetime import datetime
 from fractions import Fraction
 import functools
 from functools import partial
@@ -15,8 +14,9 @@ from homeassistant.components.stream.fmp4utils import (
     XYW_ROW,
     find_box,
 )
+from homeassistant.util import dt as dt_util
 
-FAKE_TIME = datetime.utcnow()
+FAKE_TIME = dt_util.utcnow()
 
 # Segment with defaults filled in for use in tests
 DefaultSegment = partial(