Annual extend GPG key expiration

As a follow-up to Rotate GPG keys April 2025 (#38774 - closed) • Georgi N. Georgiev | GitLab • 18.0, extend the GPG keys before they expire.

• Follow the process at https://gitlab.com/gitlab-org/gitlab-runner/-/blob/main/PROCESS.md?ref_type=heads#renew-expired-gpg-key.
• Create an issue for the next key rotation