fix types for the `run()` method

[gianpaj]

I shouldn't have to write all of this code.

interface ReplicateOutput {
 url: () => string;
 blob: () => Promise<Blob>;
}
interface ReplicateError {
 error?: string;
}
type ReplicateResponse = ReplicateOutput | ReplicateError;

const output = (await replicate.run(
 model,
 {
 input,
 },
 onProgress,
)) as ReplicateResponse;

const outputUrl = (output as ReplicateOutput).url();

const audioBuffer = await (output as ReplicateOutput).blob();