community/podman: add go-md2man makedepends
While building this locally I noticed podman's makefile fetches
go-md2man from internet with a go install command, but we have
a package for this.
This also speeds up build times a bit.
(that aside this is a no-op change that should have no impact to produced binaries, happy to get this in only when we update podman later)
cc @mpolanski