Add 'encoding' as explicit dependency

netlify/netlify-lambda#142

Author: johnnyoshika

package-lock.json

@@ -7,6 +7,7 @@
     "apollo-boost": "^0.4.7",
     "apollo-server-lambda": "^2.12.0",
     "axios": "^0.19.0",
+    "encoding": "^0.1.12",
     "graphql": "^15.0.0",
     "react": "^16.8.6",
     "react-dom": "^16.8.6",