chore: add rik and rubin as maintainers (#2408)

I would like to propose to add both Rik and Rubin as maintainers
on the project because of their dedication to the project in the
past 2+ years. They have been serving as triagers / moderators
in the past period.

I will also look forward to hand over the keys to a new guard
very soon.

Long live validator.js <3

README.md

@@ -204,6 +204,8 @@ For an alternative, have a look at Yahoo's [xss-filters library](https://github.
 
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