Update top-gh-contribs to get contributors within last 90 days

Closes #4130

- Fixed up the dependency to take a date in MS and divide it by 1k, as GH's API doesn't do MS [ref](https://github.com/novaugust/top-gh-contribs/commit/034f5fd5a08de6f03e853e521f8d2574073ce438)