fix rules_nodejs
diff --git a/buildkite/pipelines/rules_nodejs-postsubmit.json b/buildkite/pipelines/rules_nodejs-postsubmit.json
index f90b3ae..dc226c3 100644
--- a/buildkite/pipelines/rules_nodejs-postsubmit.json
+++ b/buildkite/pipelines/rules_nodejs-postsubmit.json
@@ -1,8 +1,8 @@
 {
   "platforms": {
-    "ubuntu1404": {"run_targets": "@yarn//:yarn", "build_targets": ["..."], "test_targets": ["..."]},
-    "ubuntu1604": {"run_targets": "@yarn//:yarn", "build_targets": ["..."], "test_targets": ["..."]},
-    "macos": {"run_targets": "@yarn//:yarn", "build_targets": ["..."], "test_targets": ["..."]}
+    "ubuntu1404": {"run_targets": ["@yarn//:yarn"], "build_targets": ["..."], "test_targets": ["..."]},
+    "ubuntu1604": {"run_targets": ["@yarn//:yarn"], "build_targets": ["..."], "test_targets": ["..."]},
+    "macos": {"run_targets": ["@yarn//:yarn"], "build_targets": ["..."], "test_targets": ["..."]}
   }
 }