Remove pyproject.toml (#61367)

Summary:
This reverts https://github.com/pytorch/pytorch/issues/60408, since it doesn't really give much benefit, and it ended up breaking things:

- https://github.com/pytorch/pytorch/issues/60665
- https://github.com/pytorch/pytorch/pull/60408#issuecomment-873979383

Pull Request resolved: https://github.com/pytorch/pytorch/pull/61367

Reviewed By: malfet, janeyx99

Differential Revision: D29593886

Pulled By: samestep

fbshipit-source-id: b1ba0ac7695e3eacf66a35e293080e8a1240efca

.isort.cfg

@@ -0,0 +1,6 @@
+[settings]
+include_trailing_comma=True
+multi_line_output=3
+skip=third_party
+skip_gitignore=True
+use_parentheses=True

pyproject.toml

@@ -1,12 +0,0 @@
-[build-system]
-requires = ["setuptools", "wheel"]
-build-backend = "setuptools.build_meta"
-
-[tool.isort]
-include_trailing_comma = true
-multi_line_output = 3
-skip = [
-    "third_party",
-]
-skip_gitignore = true
-use_parentheses = true