[depot_tools] annotate third_party/colorama as non security critical

https://github.com/tartley/colorama a python library that makes
ANSI escape character sequences work under MS windows.

AFAIK, the library itself is not used to perform,
nor does it perform, any of the operations, listed in
https://chromium.googlesource.com/chromium/src/+/HEAD/docs/adding_to_third_party.md#add-a-readme_chromium

Bug: 365320907
Change-Id: I2bb9301a3420b0813675c8952f8720e1395761ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5843576
Commit-Queue: Scott Lee <ddoman@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

third_party/colorama/README.chromium

@@ -5,7 +5,7 @@ Revision: b71bec90d4770d4124ad95d70cc6a4c9289bbadf
 License: BSD
 License File: LICENSE.txt
 Shipped: no
-
+Security Critical: no
 Description:
 Provides a simple cross-platform API to print colored terminal text from Python
 applications.