Bump reveal.js from 3.9.2 to 4.0.0

Bumps [reveal.js](https://github.com/hakimel/reveal.js) from 3.9.2 to 4.0.0.
- [Release notes](https://github.com/hakimel/reveal.js/releases)
- [Commits](hakimel/reveal.js@3.9.2...4.0.0)

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

Author: dependabot-preview[bot]

Diff for: package-lock.json

@@ -4,7 +4,7 @@
   "private": true,
   "dependencies": {
     "highlight.js": "^10.0.3",
-    "reveal.js": "^3.9.2"
+    "reveal.js": "^4.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.9.6",