Roll SK Tool from 876761b46493 to f9e7723e5a27

https://skia.googlesource.com/buildbot.git/+log/876761b46493..f9e7723e5a27

2021-09-09 rmistry@google.com Delete ds.MigrateData
2021-09-09 kjlubick@google.com [infra] Add now helper for changing time throughout tests.
2021-09-09 kjlubick@google.com [vfs] Use fs.FileInfo instead of os.FileInfo
2021-09-09 kjlubick@google.com [machine] Mock out times for tests and decouple firestore schema.
2021-09-09 kjlubick@google.com [tmm] Address some static analysis concerns
2021-09-09 kjlubick@google.com [tmm] Improve documentation and names.
2021-09-09 kjlubick@google.com [infra] Run RBE using the VM service account, not JSON keys.

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/sk-tool-skia
Please CC jcgregorio@google.com on the revert to ensure that a human
is aware of the problem.

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Tbr: jcgregorio@google.com
Change-Id: I83a9268ae1d0f5d8eee0571b128c6f785259806b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/447237
Commit-Queue: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
Bot-Commit: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 22cb7c6..91a459e 100644
--- a/DEPS
+++ b/DEPS
@@ -6,7 +6,7 @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling different
   # dependencies without interference from each other.
-  'sk_tool_revision': 'git_revision:a2c45e4997e0c5eabe6519f52501de1ea2e98dd6',
+  'sk_tool_revision': 'git_revision:f9e7723e5a27fbb7806a7b93434013beb55b4aac',
 }
 
 deps = {