Add CI run across OSes to run current duct against the gallery log examples

We have https://github.com/con/duct-gallery which has logs for our examples, potentially across different versions of con-duct. `con-duct` commands such as `ls`, `plot` etc must not fail when operating against those logs. It could also post generated new images (within its comment on the PR, updated if more changes, just 1 comment, do not breed many) for those gallery plots (folded within ``).

I believe the approach could be taken from

- https://github.com/stamped-principles/stamped-paper/blob/main/.github/workflows/build-pdf.yml