ci: update Node.js Docker image (#213)

.circleci/config.yml

@@ -2,7 +2,7 @@ version: 2
 jobs:
   test:
     docker:
-      - image: circleci/node:10.15
+      - image: cimg/node:16.13.2
     steps:
       - checkout
       - restore_cache:

.gitignore

@@ -5,3 +5,4 @@ working
 *.pem
 package-lock.json
 yarn-error.log
+.DS_Store