Relax requirements, workaround for weasyprint removing image rendering (due to removing cairo dep).

[rwightman]

I'm planning to base a (partially) synthetic document datapipeline on generation capabilities in this lib. As is known from issues going back 2 years, in it's current state this library cannot be installed (too many out of date dependencies), and use of weasyprint is broken after they removed pdf/image rendering.

This PR

• removes strict requirements (builds fine in recent python env)
• adds image rendering via either fitz or pypdfium2 (both are currently soft-deps). fitz is AGPL so I won't make it a hard dep, but probably worth making pypdfium2 a hard dependency.
• changes default demo args so that the augmentations are a little less aggressive and we can read the output (barely)

Tests for png/image output require a rethink.

I'd like to know if there'd be any intent on merging these changes. If I could be added as a maintainer? Otherwise I'll likely have to maintain a parallel fork w/ new pip package to be able to use in other projects.

Thanks!

[rwightman]

@laserprec looks like you've moved on from MS, but might know who to ping there if there's any interest in keeping this project alive. Thanks

[laserprec]

Hi @rwightman, thanks for your support of the repo and offer to help, and I apologize for this late response. Yes, I am no longer able to help merging PRs. I think @jgc128 and/or @amitgupte should be able to help here.