Bump mustache from 0.7.3 to 3.1.0 in /doc/src/GaussianProcess/reveal.js

Bumps [mustache](https://github.com/janl/mustache.js) from 0.7.3 to 3.1.0.
- [Release notes](https://github.com/janl/mustache.js/releases)
- [Changelog](https://github.com/janl/mustache.js/blob/master/CHANGELOG.md)
- [Commits](janl/mustache.js@0.7.3...v3.1.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

doc/src/GaussianProcess/reveal.js/package.json

@@ -24,7 +24,7 @@
   "dependencies": {
     "underscore": "~1.5.1",
     "express": "~2.5.9",
-    "mustache": "~0.7.2",
+    "mustache": "~3.1.0",
     "socket.io": "~0.9.16"
   },
   "devDependencies": {