Due to recent changes mcrypt is not available anymore
in the latest php docker image. Thus we downgrade the
base image for now.
Additionally we upgrade the Nextcloud Version to 12.0.4
as the old image provided 12.0.2, which we upgraded within
the container to 126.96.36.199. We couldn't reuse 12.0.2 as a downgrade
of our database to the 12.0.2 database is not possible.