tools: Fix gn_check_autofix.py with Python3

Bug: None
Change-Id: Ib81f02823cae4a10697566d5889d4814a0184503
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/257903
Auto-Submit: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36425}
diff --git a/tools_webrtc/gn_check_autofix.py b/tools_webrtc/gn_check_autofix.py
index 88ba0cc..1a93898 100644
--- a/tools_webrtc/gn_check_autofix.py
+++ b/tools_webrtc/gn_check_autofix.py
@@ -165,7 +165,7 @@
     return 1
 
   for error in errors:
-    error = error.split('\\n')
+    error = error.split('\n')
     target_msg = 'The target:'
     if target_msg not in error:
       target_msg = 'It is not in any dependency of'