Bump node-sass from 4.7.2 to 4.9.3

Bumps [node-sass](https://github.com/sass/node-sass) from 4.7.2 to 4.9.3.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](sass/node-sass@v4.7.2...v4.9.3)

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

Author: dependabot-support

package.json

@@ -92,7 +92,7 @@
     "mime": "^2.3.1",
     "mongoose": "~4.13.2",
     "multer": "~1.3.0",
-    "node-sass": "~4.7.2",
+    "node-sass": "~4.9.3",
     "nyc": "^12.0.2",
     "quill-url-embeds": "^1.2.5",
     "raven": "~2.6.1",