Drop Docker dependency #74
Description
Docker was the easiest way for me to bootstrap zizmor here. But it's arguably overkill, plus it isn't included in ubuntu-slim runners.
Earlier versions of this action used setup-uv + uvx zizmor. The downside to that is that uvx ... pays a Python runtime initialization cost (a pretty minor one, but still) and it makes hashing slightly more troublesome, since uvx can fetch multiple distinct architecture wheels rather than Docker fetching a multi-arch OCI image and doing the right delegation with it.