Correcting minor interface typing error

backend/src/api/bitcoin/bitcoin-api.interface.ts

@@ -108,7 +108,7 @@ export namespace IBitcoinApi {
     scriptPubKey: string;            //  (string) The hex-encoded scriptPubKey generated by the address
     isscript: boolean;               //  (boolean) If the key is a script
     iswitness: boolean;              //  (boolean) If the address is a witness
-    witness_version?: boolean;       //  (numeric, optional) The version number of the witness program
+    witness_version?: number;        //  (numeric, optional) The version number of the witness program
     witness_program: string;         //  (string, optional) The hex value of the witness program
     confidential_key?: string;       //  (string) Elements only
     unconfidential?: string;         //  (string) Elements only