Specify node engine

Author: isaacgr

package.json

@@ -12,6 +12,9 @@
   ],
   "license": "MIT",
   "bugs": "https://github.com/isaacgr/jaysonic/issues",
+  "engines": {
+    "node": ">=10.0.0"
+  },
   "keywords": [
     "jsonrpc",
     "json-rpc",
@@ -93,4 +96,4 @@
     "commander": "^6.1.0",
     "ws": "^7.1.0"
   }
-}
+}