Update GPG key for IB tar

Description

GPG signing key is tied to email address ironbank@tempemail.com. It needs to be migrated to a real email address, preferably ironbank@dsop.io. Note that the GPG key is used for the tar file on ironbank.dsop.io as well.

Acceptance Criteria

• New GPG key is generated
• GPG key is updated for Iron Bank tar
• GPG key is updated in CHT pipeline for notary signing

Definition of Done

• Documentation in place
• All MR's closed