Roll recipe dependencies (trivial).

This is an automated CL created by the recipe roller. This CL rolls recipe
changes from upstream projects (e.g. depot_tools) into downstream projects
(e.g. tools/build).


More info is at https://goo.gl/zkKdpD. Use https://goo.gl/noib3a to file a bug.
recipe_engine:
  https://crrev.com/db920908bf51fcdb0e30f686a528b25cd4876ca7 Update vpython and spec to new text protobuf. (dnj@chromium.org)


TBR=iannucci@chromium.org

Recipe-Tryjob-Bypass-Reason: Autoroller
Bugdroid-Send-Email: False
Change-Id: Idc9ee786cc2f54eb69cbd5034fb5f58370d5663a
Reviewed-on: https://chromium-review.googlesource.com/527497Reviewed-by: Recipe Roller <recipe-roller@chromium.org>
Commit-Queue: Recipe Roller <recipe-roller@chromium.org>

infra/config/recipes.cfg

@@ -15,7 +15,7 @@
   "deps": {
     "recipe_engine": {
       "branch": "master",
-      "revision": "1ec7ad4df3efbdd7224f249179390aab4a66c562",
+      "revision": "db920908bf51fcdb0e30f686a528b25cd4876ca7",
       "url": "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git"
     }
   },