Hello,
I saw letters where it was said about the miss of packages - https://www.postgresql.org/message-id/20191117163926.GB30362%40telsasoft.com
 
Faced a similar problem for the package - pldebugger12 (CentOS 7.7, yum)
Repository install from: https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
If you look at the repository then it is not there - https://download.postgresql.org/pub/repos/yum/12/redhat/rhel-7.7-x86_64/
Looked for other versions of 7x - also missing
 
Could fix this matter.
Thank you!
 
The regards,
Alexey Matveev