Merge pull request #2 from huangyanxiong01/dependabot/npm_and_yarn/mongoose-5.7.7

Bump mongoose from 4.13.19 to 5.7.7

Author: myfreax

package.json

@@ -11,7 +11,7 @@
   "license": "MIT",
   "dependencies": {
     "koa": "2",
-    "mongoose": "^4.7.1",
+    "mongoose": "^5.7.7",
     "node-mysql": "^0.4.2",
     "redis": "^2.6.3"
   },