Fix release ID not in GitHub event

[Nadock]

For new GitHub actions, it seems the release ID is not in the event json supplied to the action. This pull request would change the upload script to retrieve the release ID from the API via the tag name.

Full disclousre: I haven't had a chance to properly test this yet - it may not completly work.

Update: Turns out I can't read documentation 😂 I've solved my issue and this PR is not needed. However, if you want to use it as a basis for uploading from other event types - go for it

[JasonEtco]

Thanks for opening this @Nadock - what part of the docs ended up clarifying this for you? If there's something that should be more obvious, would love to hear it!

[Nadock]

It was mostly me not realising I was using a push event, not a release event to trigger my workflow. I didn't even initially realise you could use more than push or pull_request -- the GH docs on Actions are still very beta.

I do have some suggestions for the documentation for this project though, I'll open a new issue to details that 👍