build: bump rake from 12.3.2 to 12.3.3 in /docs

Bumps [rake](https://github.com/ruby/rake) from 12.3.2 to 12.3.3.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](https://github.com/ruby/rake/compare/v12.3.2...v12.3.3

)

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