Move repository to GitHub
There is currently 2000 CI minutes per month in Gitlab BuildStream project which is completely inadequate for this repository. Either BuildStream must apply to Gitlab opensource program (https://about.gitlab.com/handbook/marketing/community-relations/community-programs/opensource-program/) or if failing that (which is probably since main repository is not in Gitlab) this repository must be moved under Apache project in GitHub which does not have limited minutes.