devel/py-buildbot-worker: Update version 3.5.0=>3.7.0

• Use the existing buildbot users and groups
• Refactor the rc script to use the existing users. Please be informed that buildbot_worker_{uid|gid} is no longer the recommended rcvar. If a different user needs to be used the rcvar should be updated with buildbot_worker_user. Currently this defaults to buildbot and buildbot_worker_basedir defaults to a subfolder named workers under the home directory of buildbot that is /var/db/buildbot [1]
• Refactor the rc script to use the program as the command rather than using twistd as per upstream documentation

PR: 248234 [1]
Reported by: ari@ish.com.au [1]