Roll recipe dependencies (trivial).

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

The build that created this CL was
https://ci.chromium.org/b/8699562958603852401

recipe_engine:
a7ad338e9c
  a7ad338 (gbeaty@chromium.org)
      Annotate ModuleInjectionSite.__getattr__ to remove spurious err...

Please check the following references for more information:
- autoroller, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/workflow.md#autoroller
- rollback, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/workflow.md#rollback
- cross-repo dependencies, https://chromium.googlesource.com/infra/luci/recipes-py/+/main/doc/cross_repo.md

Use https://goo.gl/noib3a to file a bug.

R=iannucci@chromium.org

Recipe-Tryjob-Bypass-Reason: Autoroller
Ignore-Freeze: Autoroller
Bugdroid-Send-Email: False
Change-Id: I65e470800c451f5ac290c33cb2632cb4ec32922d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/7102410
Commit-Queue: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>

infra/config/recipes.cfg

@@ -17,7 +17,7 @@
   "deps": {
     "recipe_engine": {
       "branch": "refs/heads/main",
-      "revision": "51555fa216373080dab4008e290abc9d84878ede",
+      "revision": "a7ad338e9cfbb4c89bc5e3e8d5a8d81e3bd9dad2",
       "url": "https://chromium.googlesource.com/infra/luci/recipes-py.git"
     }
   },