Add Fedora 34

Build, unit test and system test as well as stress tests work fine on main on Fedora 34 amd64 & arm64 from staging repo.

v9_16 pipeline: https://gitlab.isc.org/isc-projects/bind9/-/pipelines/72190

v9_11 pipeline: https://gitlab.isc.org/isc-projects/bind9/-/pipelines/72191