Archive this repository

[paulbalandan]

See https://docs.github.com/en/repositories/archiving-a-github-repository/archiving-repositories

[MGatner]

Let's get final sign-off by @louisl before we complete this. I regret not getting his approval on the abandon PR.

[louisl]

It's fine with me guys, things have moved on to use PHP CS Fixer so it makes sense to archive if this isn't being maintained.