Build for pypi instead of conda

[vladsavelyev]

Simplify maintaining the conda package recipe: instead of manually changing the list of dependencies, populate them automatically from the pip requirements list.

Build cpg-hail pip package instead of conda.

[illusional]

The first half is great, I think templating the conda recipe is fine, but I'm not super comfortable with the script as it stands. The translation of pypi packages to conda packages feels risky, I think it'd be better to completely switch everything over to conda if possible, or I'd feel better about maintaining a json map or something.

I'd prefer a templating engine, or if not I think there should be tests for the templating. Build up the string completely, then write it. There's not much memory benefit doing it line by line.

[vladsavelyev]

I didn't intend to make the render_recipe.py script super reliable. Basically it's just intended to save us from manually updating the conda recipe deps. When making this PR, I first just extended the already existing Fix meta YAML CI section by adding a bunch of seds into the run: command, but then I realized it would be cleaner done in python, and finally python code got bigger and I extracted it into a separate script.

But I'm happy to keep render_recipe.py locally on my laptop, and push an already rendered recipe whenever we merge from upstream.

I think it'd be better to completely switch everything over to conda if possible, or I'd feel better about maintaining a json map or something.

The Hail team maintains a pip package, so it would make sense to switch to pip entirely. One downside is that pip doesn't have channels, so we would have to prefix the package name, e.g. cpg-hail to avoid clashes with the official package.

Ideally we don't want to diverge from the official release and have two packages. But not sure if that's possible. Currently there are a couple of dataproc changes (which will become irrelevant soon), and passing token to the backend (which we might try to upstream?), but even if these go away, we might need to diverge somewhere else.

[vladsavelyev]

Modified the workflow to build cpg-hail package instead of a conda one.