Allow creating Github Release in Draft

[aMediocreDad]

Hi,

I use this action in several projects where there is no NPM publishing, but a Github Release is the desired platform.

In these instances it is often beneficial to have the action create a "Draft" release in order to append binaries or check/test the release before publishing. An optional input that allows for the Github release that is created to be "draft" would be very useful.