Upgrade rust/crates/tokio-test to 0.4.2

Test: make
Change-Id: I169343506a12b86ff0484b2a7e197389c2a3e30c
diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 9388b50..eb7e2b0 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "e40ec3e4243f95b39a42bcc9049551b62c3058a0"
+    "sha1": "ff9b0ef7ca5a93f8fb10baba52996e755500546f"
   }
 }