Fix wrong import.

src/tscut/cli.py

@@ -11,6 +11,7 @@ from datetime import datetime, timedelta
 from os import unlink
 from shutil import copyfile, move
 from sys import exit
+from functools import cmp_to_key
 
 import coloredlogs
 import hexdump
@@ -19,7 +20,6 @@ from .tscut import (
     SupportedFormat,
     change_codec_private_data,
     check_required_tools,
-    cmp_to_key,
     compare_time_interval,
     concatenate_h264_parts,
     concatenate_h264_ts_parts,