pushing a containerized env with uppercase fails

[tomberek]

https://github.com/flox/floxenvs/actions/runs/15381008412/job/43271761814#step:6:12

Run docker tag ComfyUI:latest [ghcr.io/flox/floxenvs:ComfyUI-latest](http://ghcr.io/flox/floxenvs:ComfyUI-latest)
[11](https://github.com/flox/floxenvs/actions/runs/15381008412/job/43271761814#step:6:12)
Error parsing reference: "ComfyUI:latest" is not a valid repository/tag: invalid reference format: repository name (library/ComfyUI) must be lowercase