Bad GPG signature during automatic updates

Follow up to comment https://git.gsi.de/hpc/cluster/orion/cinc-config/-/issues/46#note_93724

Updating the package repository results in following error:

# for example, one of the compute nodes
>>> cluster-login -rn ccdev0003 -- grep CRITICAL /var/log/dnf.log    
2025-03-03T22:12:45+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T02:58:55+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T06:07:39+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T09:19:32+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T12:43:50+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T16:09:08+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T20:52:07+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-04T23:55:49+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T04:08:46+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T07:13:16+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T11:00:28+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T14:27:57+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T17:43:33+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-05T22:07:55+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-06T02:26:00+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-06T05:49:54+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature
2025-03-06T09:14:54+0100 CRITICAL Error: Failed to download metadata for repo 'slurm': repomd.xml GPG signature verification error: Bad GPG signature

Unfortunately this will break updates from all repositories.

Note that we do not versionlock the slurm* packages on Orion, see orion/cinc-config/roles/4.0/dnf_versionlock.rb#L32, means updates are installed automatically.