update elasticsearch dependency

Author: Yanlong Wang

package.json

@@ -16,7 +16,7 @@
   },
   "main": "lib/mongoosastic.js",
   "dependencies": {
-    "elasticsearch": "^4.0.x",
+    "elasticsearch": "^8.2.0",
     "lodash": "^3.10.1",
     "nop": "^1.0.0"
   },