Change PGP Release Key for Releases of `oscal-cli`

[aj-stein-nist]

User Story:

As an oscal-cli user, in order to ensure I have a signed release from a trusted identity from the NIST OSCAL Team, I would like an updated key belonging to a current developer or a release signing alias that belongs to appropriate members of the development team.

Goals:

• Replace Dave Waltermire's PGP key with another for signing releases in Maven as he has rolled off the project

Dependencies:

{Describe any previous issues or related work that must be completed to start or complete this issue.}

Acceptance Criteria

• All website and readme documentation affected by the changes in this issue have been updated.
• A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

[aj-stein-nist]

I have updated documentation in #135 per recent community feedback but will need to update the README again when I shift to the new key for the next release.