fix: remove beta and release to Maven

[Mercy811]

Summary

• Remove "beta" in README
• This PR is mainly for releasing another patch release to Maven as v1.12.0 is only released to Github but not to Maven

Checklist

• [ ] Does your PR title have the correct title format?
• Does your PR have a breaking change?:

[justin-fiedler]

nit: I usually also prefix the commit messages e.g. fix: updated README

[github-actions[bot]]

:tada: This PR is included in version 1.12.1 :tada:

The release is available on:

• GitHub release
• v1.12.1

Your semantic-release bot :package::rocket: