Upgrade dependencies

package.json

@@ -46,7 +46,7 @@
     "katex": "^0.10.0",
     "mathjax-node": "^2.1.1",
     "moemark": "^0.3.10",
-    "moment": "^2.15.0",
+    "moment": "^2.23.0",
     "msgpack-lite": "^0.1.26",
     "multer": "^1.2.0",
     "mysql2": "^1.6.4",
@@ -58,7 +58,7 @@
     "request": "^2.74.0",
     "request-promise": "^4.1.1",
     "sendmail": "^1.1.1",
-    "sequelize": "^4.41.2",
+    "sequelize": "^5.0.0-beta.15",
     "session-file-store": "^1.0.0",
     "socket.io": "^2.2.0",
     "stream-to-string": "^1.1.0",