fix: set minimum node.js version to >= 12

Author: brettstack

package.json

@@ -28,7 +28,7 @@
  "url": "https://github.com/CodeGenieApp/serverless-express.git"
  },
  "engines": {
- "node": ">=14"
+ "node": ">=12"
  },
  "publishConfig": {
  "access": "public"