chore: add engines field to package.json

package.json

@@ -67,5 +67,8 @@
     "supertest": "^4.0.2",
     "ts-node": "^8.5.2",
     "typescript": "^3.7.2"
+  },
+  "engines": {
+    "node": "10.x"
   }
 }