build: Use `"setuptools>=42" in build-system requires in pyproject.toml

[matthewfeickert]

"setuptools>=30.3.0" should be "setuptools>=42"; anything before 42 was too buggy to be used with pyproject.toml (40-42), or didn't support pyproject.toml at all. (technically, PEP 517)

Originally posted by @henryiii in #1773 (comment)

So

pyhf/pyproject.toml

Lines 1 to 3 in b091985

	[build-system]
	# Minimum requirements for the build system to execute.
	requires = ["wheel", "setuptools>=30.3.0", "attrs>=17.1", "setuptools_scm[toml]>=3.4"]

should be

requires = ["wheel", "setuptools>=42.0.0", "attrs>=17.1", "setuptools_scm[toml]>=3.4"]

[RishiKumarRay]

@matthewfeickert i would like to take this, is this one available?

[RishiKumarRay]

@matthewfeickert is it available?