chore: install yarn

ObservedObserver · ObservedObserver · commit 43fef06714b6 · 2022-07-01T12:23:08.000+08:00
diff --git a/buildspec.yml b/buildspec.yml
@@ -7,6 +7,7 @@ phases:
     commands:
       - echo Install deps
       - n 16
+      - npm install --global yarn
       - yarn install
   build:
     commands:
