Fix deprecated sre_constants

sre_constants is deprecated in favor of re.

src/nohang

@@ -7,7 +7,7 @@ from time import sleep, monotonic
 from operator import itemgetter
 from sys import stdout, stderr, argv, exit
 from re import search
-from sre_constants import error as invalid_re
+from re import error as invalid_re
 from signal import signal, SIGKILL, SIGTERM, SIGINT, SIGQUIT, SIGHUP, SIGUSR1