BUG #17175: The aarch64 repo is missing repomd.xml.asc metadata file, fails GPG verification

The following bug has been logged on the website:

Bug reference:      17175
Logged by:          Guillermo Pérez
Email address:      bishillo@gmail.com
PostgreSQL version: 10.18
Operating system:   rhel-8-aarch64
Description:

Check:

https://download.postgresql.org/pub/repos/yum/10/redhat/rhel-8-aarch64/repodata/

There is no 'repomd.xml.asc' file, needed for GPG verification. The package
installation fails with:

#5 157.0 PostgreSQL common RPMs for RHEL/CentOS 8 - aarc 837  B/s | 488  B
  00:00
#5 157.0 Error: Failed to download metadata for repo 'pgdg-common':
repomd.xml GPG signature verification error: Bad GPG signature

While there is a `--nogpgcheck` flag, that solution disables all gpg
verification.

The file is present in other architectures:

https://download.postgresql.org/pub/repos/yum/10/redhat/rhel-8-x86_64/repodata/