Fix wrong-import-order pylint errors in quality_assessment.signal_processing module.

Bug: webrtc:10924
Change-Id: I9aeb062f1e4b4e061192b42b9a1f8b061fbbb8c2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150646
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28989}

modules/audio_processing/test/py_quality_assessment/quality_assessment/signal_processing.py

@@ -10,10 +10,10 @@
 """
 
 import array
-import enum
 import logging
 import os
 import sys
+import enum
 
 try:
   import numpy as np