support prereleases

**Is your feature request related to a problem? Please describe.**
GitHub releases can be marked as prerelease. It would make sense to do this for release candidates.

**Describe the solution you'd like**
An optional `prerelease` input that defaults to `false` which we could trigger from our release action in consuming projects.

**Describe alternatives you've considered**
Manually updating releases once they're created, as I've done [with cucumber-js](https://github.com/cucumber/cucumber-js/releases).

**Additional context**
Not a high priority - we're doing it when publishing to npm which is important as it affects user installs, GitHub is more of a reference point.

Inizia individuando le dichiarazioni degli input dell’azione e il punto di ingresso per la creazione di una release GitHub. Aggiungi quindi l’input opzionale prerelease con valore predefinito false, poi verifica che la release generata rifletta l’impostazione prerelease richiesta, lasciando invariato il comportamento esistente.

Scritto dal modello di indicizzazione a partire dal testo della issue.