selftest: Use now() instead of utcnow()

utcnow() is deprecated and will be removed in a future version of Python.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

selftest/subunithelper.py

@@ -483,7 +483,7 @@ class PerfFilterOps(unittest.TestResult):
     def get_time(self):
         if self.suite_has_time:
             return self.latest_time
-        return datetime.datetime.utcnow()
+        return datetime.datetime.now(tz=datetime.timezone.utc)
 
     def startTest(self, test):
         self.seen_output = True