Improve benchmark installation speed

[benjaminglass1]

This solves a problem noticed while installing benchmarks and watching htop. A significant amount of time per installation is wasted checking package version that have already been checked. This PR caches those versions.

I also fixed one or two minor Ruff lints in the files I touched.

[benjaminglass1]

Test failures look the same as those on main.

[benjaminglass1]

@xmfan Please take a second look, I had to rewrite this after realizing this function is also used to validate that package versions haven't changed after installing benchmarks (which caching would invalidate). Currently getting some timing runs, but I still expect roughly the same speedup.

[benjaminglass1]

On my machine, installing all benchmarks on main takes roughly 35 minutes. With this change, installing all benchmarks takes roughly 12 minutes. These timings are obviously super variable, but that hopefully gives a sense of how impactful this change is.

The main reason for this is that we checked the version of several dependencies twice per benchmark. We got the version by importing the package in a new subprocess and querying __version__. For torch, this takes 2-3 seconds (on my machine), so that's a minute wasted every 10-15 packages. The new version queries PEP 566 metadata from the package in less than a millisecond, effectively eliminating the delay.