chore(deps): Bump billboard.js from 3.15.0 to 3.16.0 in /site

Bumps [billboard.js](https://github.com/naver/billboard.js) from 3.15.0 to 3.16.0.
- [Release notes](https://github.com/naver/billboard.js/releases)
- [Changelog](https://github.com/naver/billboard.js/blob/master/CHANGELOG.md)
- [Commits](naver/billboard.js@3.15.0...3.16.0)

---
updated-dependencies:
- dependency-name: billboard.js
  dependency-version: 3.16.0
  dependency-type: indirect
...

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

Author: dependabot[bot]