Release v1.39.0

What's Changed

• fix(secrets): exit non-zero when the vault rejects a secret by @anirudhwarrier in #618
• Add Stellar support to cre workflow simulate by @karen-stepanyan in #612
• fix(build): build with Go 1.27.3 to distrust compromised eMudhra CAs by @j-nowak in #621
• fix(client): verify TLS certificates on Workflow Registry RPC connections by @j-nowak in #622
• Update staging url by @timothyF95 in #620

Full Changelog: v1.38.0...v1.39.0