Update to latest package:test

Change-Id: I01c691ab45a1a3aaa3eb384dbafb00d1b45fd13f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104642
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Nate Bosch <nbosch@google.com>
diff --git a/DEPS b/DEPS
index 1de6d51..efa5353 100644
--- a/DEPS
+++ b/DEPS
@@ -133,7 +133,7 @@
   "test_process_tag": "1.0.3",
   "term_glyph_tag": "1.0.1",
   "test_reflective_loader_tag": "0.1.8",
-  "test_tag": "test-v1.6.1",
+  "test_tag": "test-v1.6.4",
   "typed_data_tag": "1.1.6",
   "unittest_rev": "2b8375bc98bb9dc81c539c91aaea6adce12e1072",
   "usage_tag": "3.4.0",