chore: pull Releaser keys from keyring instead of README

[nschonni]

Description

Doesn't replace the way the keys are embedded in the Dockerfiles, but use the newer keyring file to read the fingerprints.

Motivation and Context

Testing Details

Example Output(if appropriate)

Types of changes

• Documentation
• Version change (Update, remove or add more Node.js versions)
• Variant change (Update, remove or add more variants, or versions of variants)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (none of the above)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• All new and existing tests passed.

[aduh95]

I don't really see the point, this does not change the fact that building our docker images depend on the external key servers.

[MikeMcC399]

If the keyring is being used as source, should the process check for expired keys before using them?

pub   rsa3072 2022-05-17 [SC] [expired: 2026-07-08]
      890C08DB8579162FEE0DF9DB8BEAB4DFCF555EF4
uid           [ expired] RafaelGSS <rafael.nunu@hotmail.com>

See also #2591