Debugging doesn't work

[Debug via breakpoints](https://developers.cloudflare.com/workers/observability/local-development-and-testing/#debug-via-breakpoints) doesn't seem to be working properly with async handle or execute.

```
async execute(request: Request) {
const response = await doSomething(request);
return response;
}
```

Setting a breakpoint at `const response = await doSomething(request);` will pause but the response is returned (using Postman) and I can't step over to the next line.

Seems like [this](https://github.com/cloudflare/itty-router-openapi/blob/e1272be6c2e0626ff1fc19e31fb2b822beda5f49/src/openapi.ts#L189) needs an async/await (maybe?)

Start with the linked debugging documentation and the referenced src/openapi.ts line 189. Reproduce the breakpoint behavior using an async execute(request) handler and Postman, then trace how the handler's promise is processed. Done means stepping past the await reaches the next line normally while the response remains correct.

Written by the indexing model from the issue text.