It faiuls with:
Downloading packages:
warning: /var/cache/yum/x86_64/7/Webmin/packages/webmin-2.301-1.noarch.rpm: Header V4 RSA/SHA256 Signature, key ID 8916f2a2: NOKEY
Retrieving key from https://www.webmin.com/jcameron-key.asc
The GPG keys listed for the “Webmin Distribution Neutral” repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.
This is the 8916f2a2 key—the new Webmin developers key. If you don’t have it installed, either install it or grab a package that’s still signed with Jamie’s old signature.