[infra] Supply revision as target_branch to bot_update

Change-Id: I5d7f92e2f26ebca6b644d09f2f3ea5d443c1e3d6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/215421
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>
Reviewed-by: Edward Lemur <ehmaldonado@google.com>
11 files changed