Add maintainers for this package

[AlexHartford]

It seems there is much latency for @Realank to merge changes, so I would suggest if you do not have time to maintain this package that many rely on (at least review/merge other's PRs) you should please allow some others to do so on your behalf.

Your package will likely die if it is not promptly brought up to support null-safety. A PR has already been raised to do so.

Thanks for your consideration. I and many others would be happy to see this package continue to grow.