Add michaelpj as the maintainer for lsp packages

[michaelpj]

I'd like to get the lsp packages into stackage. I'm not sure what I'm doing, so let's see how this goes!

Checklist:

• Meaningful commit message, eg add my-cool-package (please don't mention build-constraints.yml)
• At least 30 minutes have passed since uploading to Hackage
• If applicable, required system libraries are added to 02-apt-get-install.sh or 03-custom-install.sh
• (optional) Package is compatible with the latest version of all dependencies (Run cabal update && cabal outdated)
• (optional) Package have been verified to work with the latest nightly snapshot, e.g by running the [verify-package script](https://github.com/commercialhaskell/stackage/blob/master/verify-package

[andreasabel]

I extended this PR here:

• lsp #7185

[michaelpj]

Thanks!