tl: create a github action for github releases

[philips]

It is a good idea for build/release pipelines to confirm that a release is successfully added to the asset transparency log.

So, lets try and create a GitHub action that does that for tl releases and may act as a template for other projects.

References:

• GitHub action for release

[philips]

Done! https://github.com/transparencylog/publish-releases-asset-transparency-action