Cleaned up configuration for isort and black

[JonathanWenger]

In a Nutshell

Configuration between linters isort and black was only handled in pre-commit hooks and could lead to conflicts.

In Detail

When running pre-commit hooks and also locally installing black via the instructions in CONTRIBUTING.md one could end up with different versions / settings leading to reformatting from the pre-commit hooks every commit. I also fixed the exclusions in the pre-commit configuration along the way, since it was throwing warnings:

 ▶ git commit -m "foo"
[WARNING] The 'exclude' field in hook 'flake8' is a regex, not a glob -- matching '/*' probably isn't what you want here
[WARNING] The 'exclude' field in hook 'black' is a regex, not a glob -- matching '/*' probably isn't what you want here
[WARNING] The 'exclude' field in hook 'isort' is a regex, not a glob -- matching '/*' probably isn't what you want here
[WARNING] The 'exclude' field in hook 'require-ascii' is a regex, not a glob -- matching '/*' probably isn't what you want here
[WARNING] The 'exclude' field in hook 'forbid-binary' is a regex, not a glob -- matching '/*' probably isn't what you want here

[JonathanWenger]

It seems like there are some inconsistencies in the import formatting in the current library. Let me know if you're fine with me just reformatting the imports in this PR.

[Balandat]

How do you (and @gpleiss, @jacobrgardner) feel about using µfmt (https://ufmt.omnilib.dev/en/stable/)? This takes care of the conflicts between black and isort, we've been using it without issues in BoTorch for a long time now.

[gpleiss]

I am 100% in favor of any dev practices you all use for BoTorch :)

[Balandat]

Done in #56.