update dep

package.json

@@ -8,20 +8,20 @@
     "dependencies": {
         "axios": "^0.19.0",
         "bson": "^4.0.2",
-        "hljs": "^6.2.3",
+        "highlight.js": "^9.18.1",
         "js-yaml": "^3.13.1",
         "koa": "^2.11.0",
         "koa-body": "^4.1.1",
         "koa-morgan": "^1.0.1",
         "koa-router": "^7.4.0",
-        "koa-static": "^5.0.0",
+        "koa-send": "^5.0.0",
         "lodash": "^4.17.15",
         "markdown-it": "^10.0.0",
         "markdown-it-katex": "^2.0.3",
         "mongodb": "^3.5.5",
         "nodemailer": "^6.3.1",
         "nunjucks": "^3.2.1",
-        "sockjs": "^0.3.20"
+        "socket.io": "^2.3.0"
     },
     "devDependencies": {
         "eslint": "^6.6.0"