An odd request... looking for src RPMS for last PostgreSQL 9 release.

Greetings,

I know this is an odd request, and that the better answer is to use a newer
release, but I am needing to resurrect an old project in a short amount of
time. That project used several FDW modules last compiled under 9.1 on
CentOS 5, and we need to get a demo site up with these modules ASAP. Can
anyone tell me how I might be able to get the source RPMs for a release
this old (probably looking for 9.6.23) so that I can rebuild the packages
for RHEL (Rocky) 9?

Also, any recommendations on which list to talk to about making the
necessary changes to get these FDW modules compiling under something more
modern? I have already spent a week trying to navigate the changes which
appear to have taken place around 12 or 13 to many headaches.

Thanks in advance,
- Doug