Upgrade to latest Nitro version

## Is your feature request related to a problem?

When I'm trying to use `ratelimit` alongside Nitro 3, I get some type errors.

## Describe the solution you'd like

Upgrade to Nitro 3, ie. replace

```import type { H3Event } from 'h3'```

by

```import type { H3Event } from 'nitro'```