osbuild/osbuild v28 on GitHub

CHANGES WITH 28:

Add a new option to the org.osbuild.qemu assembler that controls
the qcow2 format version (qcow2_compat).
Add history entries to the layers of OCI archives produced by the
org.osbuild.oci-archive stage. This fixes push failures to quay.io.
Include only a specific, limited set of xattrs in OCI archives produced by
the org.osbuild.oci-archive stage. This is specifically meant to exclude
SELinux-related attributes (security.selinux) which are sometimes added
even when invoking tar with the --no-selinux option.
The package metadata for the org.osbuild.rpm stage is now sorted by
package name, to provide a stable sorting of the array independent of
the rpm output.
Add a new runner for Fedora 35 (org.osbuild.fedora35) which is
currently a symlink to the Fedora 30 runner.
The org.osbuild.ostree input now uses ostree-output as temporary
directory and its description got fixed to reflect that it does
indeed support pipeline and source inputs.
devcontainer: Include more packages needed for the Python extension and
various tools to ease debugging and development in general. Preserve
the fish history across container rebuilds.
Stage tests are writing the prodcued metadata to /tmp so the actual
data can be inspected in case there is a deviation.
CI: Start running images tests against 8.4 and execute image_tests directly
from osbuild-composer-tests. Base CI images have been updated to Fedora 33.

Contributions from: Achilleas Koutsou, Alexander Todorov, Christian Kellner,
David Rheinsberg

— Berlin, 2021-04-08