Remove deprecated datetime.utcnow()

Python 3.12 deprecates the use of datetime.utcnow()[1].

This patch moves diskimage-builder to use datetime.now(datetime.timezone.utc).

[1] https://docs.python.org/3/library/datetime.html#datetime.datetime.utcnow

Change-Id: I7b2430248e1709e7fb7631bd7dd2e828a3a5d7d5

diskimage_builder/lib/outfilter.py

@@ -62,7 +62,7 @@ def main():
         if skip_line(line):
             continue
 
-        now = datetime.datetime.utcnow()
+        now = datetime.datetime.now(datetime.timezone.utc)
         ts_line = ("%s | %s" % (
             now.strftime("%Y-%m-%d %H:%M:%S.%f")[:-3],
             line))