Update Chrome (for Testing) PIN

Chromium pin updated to 140.0.7288.0

Roll created at https://cr-buildbucket.appspot.com/build/8709675907699315809

Bug: none
Change-Id: I4fb39f7d87fddb6498c8af7b7c7b3952d445b96a
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6726035
Commit-Queue: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>

Author: devtools-ci-autoroll-builder

DEPS

@@ -49,7 +49,7 @@ vars = {
   # Chrome version used for tests. It should be regularly updated to
   # match the Canary version listed here:
   # https://googlechromelabs.github.io/chrome-for-testing/last-known-good-versions.json
-  'chrome': '140.0.7287.0',
+  'chrome': '140.0.7288.0',
 
   # 'magic' text to tell depot_tools that git submodules should be accepted but
   # but parity with DEPS file is expected.