Instead of relying on a broken-ish installation
of an older package from FreeBSD 11, hand-generate
a package named `zsh` with no contents and a version
number of `0`. It can be installed on any architecture
and any revision of FreeBSD sucessfully, and it will
always be eligible for upgrade.
Including small filesize out-of-date package from
FreeBSD 11 package repository, because FreeBSD 11 is
currently EOL. This test might fail at some point in the
future if the pkg utility in a FreeBSD version > 14
makes breaking changes that prevents it from installing
older package formats.
If that occurs, the fix is to replace
`files/freebsd-release-manifests-20210413__FreeBSD_11.pkg`
with the version of freebsd-release-manifests from the oldest
non-breaking release of FreeBSD, and update the
references to it in tasks/main.yml accordingly.
