Bump bemerge eapi
It complained that EAPI=6 is too old. It works just fine with EAPI=8
Fixes https://bugs.gentoo.org/939060
Removed obsolete stages of the pipeline:
- we don't do fetch checks as we deleted most of zfs code
- we don't use released container images as we don't have the rest of the pipeline running anyway
- the most recent repoman docker image is from 2 years ago, so it complains about anything newer than that
Edited by Aleksander Mistewicz