Roll recipe dependencies (trivial).

This is an automated CL created by the recipe roller. This CL rolls recipe
changes from upstream projects (depot_tools) into this repository.

depot_tools:
  https://crrev.com/da4b6c6e041ecde317f38943b977830f829d2af7 (ehmaldonado@google.com)
    git-cl: Use mock.patch instead of custom mock.
  https://crrev.com/15a9b8cc5ddc0262ef293b2c419d609875c32b22 (ehmaldonado@google.com)
    git-cl: Use scm.GIT.FetchUpstreamTuple.

More info is at https://goo.gl/zkKdpD. Use https://goo.gl/noib3a to file a bug.

TBR=borenet@google.com

Recipe-Tryjob-Bypass-Reason: Autoroller
Bugdroid-Send-Email: False
Change-Id: Ibe0647e96ee6fdddccd6f11dd8182030682024a9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/270500
Reviewed-by: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>

Author: recipe-roller

infra/config/recipes.cfg

@@ -14,7 +14,7 @@
   "deps": {
     "depot_tools": {
       "branch": "master",
-      "revision": "da8eec5db306642b0f959b419fd10e0051763a75",
+      "revision": "15a9b8cc5ddc0262ef293b2c419d609875c32b22",
       "url": "https://chromium.googlesource.com/chromium/tools/depot_tools.git"
     },
     "recipe_engine": {