Bump ejs from 2.5.5 to 3.1.7

Bumps [ejs](https://github.com/mde/ejs) from 2.5.5 to 3.1.7.
- [Release notes](https://github.com/mde/ejs/releases)
- [Commits](mde/ejs@v2.5.5...v3.1.7)

---
updated-dependencies:
- dependency-name: ejs
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -14,7 +14,7 @@
     "bcryptjs": "^2.4.3",
     "bluebird": "^3.5.5",
     "cheerio": "^0.20.0",
-    "ejs": "2.5.5",
+    "ejs": "3.1.7",
     "grunt": "^1.0.3",
     "grunt-contrib-clean": "^2.0.0",
     "grunt-contrib-coffee": "^2.1.0",