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.

Empieza localizando las declaraciones de entrada de la acción y el punto de entrada para la creación de releases de GitHub. Añade la entrada opcional prerelease con un valor predeterminado false y, después, verifica que el release generado refleje la configuración de prerelease solicitada, mientras el comportamiento existente permanece sin cambios.

Escrito por el modelo de indexación a partir del texto del issue.