Update dependency ejs to v3

Author: mend-for-g.yxqyang.asia[bot]

package.json

@@ -12,7 +12,7 @@
   },
   "dependencies": {
     "async": "^2.6.0",
-    "ejs": "^2.5.6",
+    "ejs": "^3.1.10",
     "express": "^4.15.2",
     "express-session": "^1.15.6",
     "request-promise": "^4.2.2"