Roll recipe dependencies (trivial).

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

The build that created this CL was
https://ci.chromium.org/b/8751807272200618145

dart:
https://dart.googlesource.com/recipes.git/+/38e15551ef76d2c3b6f373c170b74809e4eebaa7
  38e1555 (sortie@google.com)
      Use GCE Credentials for RBE.

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=flutter-infra@grotations.appspotmail.com

Recipe-Tryjob-Bypass-Reason: Autoroller
Ignore-Freeze: Autoroller
Bugdroid-Send-Email: False
Change-Id: Iabc96587225f7b5fa44b470a806816b3c713e474
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/56860
Commit-Queue: flutter-prod-builder@chops-service-accounts.iam.gserviceaccount.com <flutter-prod-builder@chops-service-accounts.iam.gserviceaccount.com>
Bot-Commit: flutter-prod-builder@chops-service-accounts.iam.gserviceaccount.com <flutter-prod-builder@chops-service-accounts.iam.gserviceaccount.com>
diff --git a/infra/config/recipes.cfg b/infra/config/recipes.cfg
index 8e68620..735f116 100644
--- a/infra/config/recipes.cfg
+++ b/infra/config/recipes.cfg
@@ -22,7 +22,7 @@
   "deps": {
     "dart": {
       "branch": "refs/heads/main",
-      "revision": "e8f97168fc7fd7435fa4f2998204513505f8fbf8",
+      "revision": "38e15551ef76d2c3b6f373c170b74809e4eebaa7",
       "url": "https://dart.googlesource.com/recipes.git"
     },
     "depot_tools": {