[py3.12] Use a Raw String in post_build_ninja_summary

depot_tools/post_build_ninja_summary.py:5: SyntaxWarning: invalid
escape sequence '\d'
  """Summarize the last ninja build, invoked with ninja's -C syntax.

Bug: chromium:1487454
Change-Id: I117b94872d65552168c295b4886ccb48a2fd4052
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4986821
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Ho Cheung <uioptt24@gmail.com>

post_build_ninja_summary.py

@@ -2,7 +2,7 @@
 # Copyright (c) 2018 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
-"""Summarize the last ninja build, invoked with ninja's -C syntax.
+r"""Summarize the last ninja build, invoked with ninja's -C syntax.
 
 This script is designed to be automatically run after each ninja build in
 order to summarize the build's performance. Making build performance information