Implement set-secret (#141)

* Implement set-secret

* Update RELEASES.md

* Feedback

packages/core/src/core.ts

@@ -51,7 +51,6 @@ export function exportSecret(name: string, val: string): void {
   // the runner will error with not implemented
   // leaving the function but raising the error earlier
   issueCommand('set-secret', {}, val)
-  throw new Error('Not implemented.')
 }
 
 /**