BUG #18270: RPM signing GPG key URL changed 2024-01-03

The following bug has been logged on the website:

Bug reference:      18270
Logged by:          Bas
Email address:      bas.meijer@me.com
PostgreSQL version: 13.13
Operating system:   RHEL8
Description:

Please create a redirect on your web farm if you change the URL of a
critical file like the GPG key used to sign RPMs.

Old URL: https://download.postgresql.org/pub/repos/yum/RPM-GPG-KEY-PGDG
New URL:
https://download.postgresql.org/pub/repos/yum/keys/PGDG-RPM-GPG-KEY-RHEL

Related: https://github.com/jfrog/JFrog-Cloud-Installers/issues/361