Update to the latest package:async

Change-Id: Id8603f7be61c0ae394f2c3881658819bec1428e0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/197105
Auto-Submit: Nate Bosch <nbosch@google.com>
Commit-Queue: Nate Bosch <nbosch@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>
diff --git a/.dart_tool/package_config.json b/.dart_tool/package_config.json
index 761daab..bc6c454 100644
--- a/.dart_tool/package_config.json
+++ b/.dart_tool/package_config.json
@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2021-04-23T17:16:06.111697",
+  "generated": "2021-04-27T11:20:39.928830",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
diff --git a/DEPS b/DEPS
index 4fda08e..8a72859 100644
--- a/DEPS
+++ b/DEPS
@@ -73,7 +73,7 @@
 
   # Revisions of /third_party/* dependencies.
   "args_rev": "d8fea36c10ef96797be02e3d132d572445cd86f4",
-  "async_rev": "376c0fe95fa6fe7a5a6c41ef7b4585085c826f89",
+  "async_rev": "06774f59a7cf9780e08148298d438c1043e2b063",
   "bazel_worker_rev": "0885637b037979afbf5bcd05fd748b309fd669c0",
   "benchmark_harness_rev": "c546dbd9f639f75cd2f75de8df2eb9f8ea15e8e7",
   "boolean_selector_rev": "665e6921ab246569420376f827bff4585dff0b14",