Roll recipe dependencies (trivial).

R=
BUG=
TBR=luqui@chromium.org

Review URL: https://codereview.chromium.org/1666313002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@298598 0039d316-1c4b-4281-b951-d872f2087c98

infra/config/recipes.cfg

@@ -5,5 +5,5 @@ deps {
   project_id: "recipe_engine"
   url: "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git"
   branch: "master"
-  revision: "20e34592ee5150d3ecbbd3e8840c91e525c87de1"
+  revision: "21f731d1abad011a106407bb7b357d7abc21401f"
 }