[3006.x] Replace expired pubkey for security reporting

[ScriptAutomate]

What does this PR do?

• Updates the pubkey, listed for security reporting, with a key that is valid until June, 2028
• This is an extension of the problem originally found in [TECH DEBT] security@saltstack.com gpg key has expired #61834
  • Original, partial solution of Update gpg key #61835 will expire next year
  • Newly generated key, in this PR, expires 2028-06-11

What issues does this PR fix or reference?

Fixes #61834

Previous Behavior

• Public key, shown in SECURITY.md for security reporting, expired in October, 2022
• Public key, shown in doc/security/index.rst for security reporting, differs from SECURITY.md and is valid until 2025

New Behavior

• New public key, shown the same in both SECURITY.md and doc/security/index.rst for security reporting, is now valid until June, 2028

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs

Commits signed with GPG?

Yes