Update config.yml

Author: teesloane

.circleci/config.yml

@@ -1,22 +1,22 @@
-version: 2
+version: 2.1
 jobs:
   build:
     working_directory: ~/mern-starter
     docker:
-      - image: circleci/node:4.8.2
-      - image: mongo:3.4.4
+      - image: circleci/node:10.16.3
+      - image: mongo:4.2.0
     steps:
       - checkout
       - run:
           name: update-npm
           command: 'sudo npm install -g npm@5'
       - restore_cache:
-          key: dependency-cache-{{ checksum "package.json" }}
+          key: dependency-cache-{{ checksum "package-lock.json" }}
       - run:
           name: install-npm-wee
           command: npm install
       - save_cache:
-          key: dependency-cache-{{ checksum "package.json" }}
+          key: dependency-cache-{{ checksum "package-lock.json" }}
           paths:
             - ./node_modules
       - run: