Update protobuf version pulled in by vpython to 3.6.1.

Bug: 922145
Change-Id: I2f4259502b812e3bb4b411ca65318000bd3c7286
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1918310
Commit-Queue: Yun Liu <yliuyliu@google.com>
Auto-Submit: John Budorick <jbudorick@chromium.org>
Reviewed-by: Yun Liu <yliuyliu@google.com>
Cr-Commit-Position: refs/heads/master@{#715849}

.vpython

@@ -116,10 +116,11 @@ wheel: <
 >
 
 # Used by:
-#   chrome/browser/policy/test/policy_testserver.py
+#   build/android/pylib/local/emulator/avd.py
+#   components/policy/test_support/policy_testserver.py
 wheel: <
   name: "infra/python/wheels/protobuf-py2_py3"
-  version: "version:3.2.0"
+  version: "version:3.6.1"
 >
 wheel: <
   name: "infra/python/wheels/six-py2_py3"