Mark dependency on Node.js 12.x or later

Author: kennu

README.md

@@ -8,6 +8,8 @@ Copyright [Nordcloud](https://nordcloud.com) 2017-2020. Released under the MIT l
 This plugin provides support for managing multiple AWS CloudFormation stacks
 in your Serverless 1.x service (serverless.yml).
 
+The plugin requires Node.js 12.x or later due to use of Object.fromEntries().
+
 Normally, Serverless creates a single CloudFormation stack which contains
 all your CloudFormation resources. If you ever delete your service, these
 resources are also deleted, including data stored in S3 or DynamoDB.

package-lock.json

@@ -9,5 +9,8 @@
   },
   "dependencies": {
     "lodash.merge": "^4.6.2"
+  },
+  "engines": {
+    "node": ">=12.0.0"
   }
 }