Release push tool as a single binary

Currently the push tool residing in the `push` subdirectory needs to be built manually. That means in most of my pipelines, I have to clone the repo and build the tool.

It would be great, if you could version, pre-build and provide a GitHub release for it, so that this can be downloaded from GitHub in automated jobs and even have renovate propose updates.

Start by inspecting the push/ subdirectory and its current manual build process. Determine how the tool should be versioned and packaged for GitHub releases and automated pipeline downloads, including what Renovate can detect. Done means a documented, versioned single-binary release is available for automated jobs.

Written by the indexing model from the issue text.