Fix export type GeneratedSecretStorageKey

Author: florianduros

src/crypto/api.ts

@@ -19,7 +19,7 @@ import { IKeyBackupInfo } from "./keybackup";
 import { GeneratedSecretStorageKey } from "../crypto-api";
 
 /* re-exports for backwards compatibility. */
-export { CrossSigningKey, GeneratedSecretStorageKey as IRecoveryKey } from "../crypto-api";
+export type { CrossSigningKey, GeneratedSecretStorageKey as IRecoveryKey } from "../crypto-api";
 
 export type {
     ImportRoomKeyProgressData as IImportOpts,