Update DevTools DEPS (trusted)

Rolling third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/fab0a42..977c374

Roll created at https://cr-buildbucket.appspot.com/build/8715258947028750273

Bug: none
Change-Id: I26fd0414f03479196771c7e8949c2dba60ad3941
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6532269
Bot-Commit: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Devtools Autoroller <devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>

Author: devtools-ci-autoroll-builder

DEPS

@@ -18,7 +18,7 @@ vars = {
   'buildtools_revision': '077a66f30fcf281b066fafb6dfc60818c238efb6',
 
   'depot_tools_url': 'https://chromium.googlesource.com/chromium/tools/depot_tools.git',
-  'depot_tools_revision': 'fab0a4296b8830c569a4dc82285bfb58a5c2fca8',
+  'depot_tools_revision': '977c37458fda472d8822a8b57e4a83a7bc747471',
 
   'inspector_protocol_url': 'https://chromium.googlesource.com/deps/inspector_protocol',
   'inspector_protocol_revision': '6d1ae0f13aae6ad381ca31b17b88a0f5af29ca94',