Require the pmbootstrap version where we added a workdir migration to
change pmaports git URLs from gitlab.com to gitlab.postmarketos.org.

pmaports at gitlab.com will be fast-forwarded to this commit once, so
users who still have this archived repository configured as upstream
will be notified of this change after next git pull and trying to use
pmbootstrap <2.3.2 with it.

Related: https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/tags/2.3.2
Related: pmbootstrap issue 2471