remove cython dependency, remove setup.cfg

[jameslamb]

Came here looking to remove the setup.cfg file, inspired by rapidsai/raft#2532.

But this PR uncovered a few other packaging things to be cleaned up. Proposes:

• removing Cython dependency
• aligning cmake_minimum_required() version with the one from the conda recipe, and with what RAPIDS has been using for the last few releases
• removing maptlolib dependency for benchmarks

Notes for Reviewers

How is it safe to remove Cython?

As far as I can tell, this project doesn't have any Cython code. It is building a shared library and then loading it with ctypes:

legate-raft/legate_raft/library.py

Lines 21 to 26 in 3260952

	def dlopen_no_autoclose(ffi: Any, lib_path: str) -> Any:
	# Use an already-opened library handle, which cffi will convert to a
	# regular FFI object (using the definitions previously added using
	# ffi.cdef), but will not automatically dlclose() on collection.
	lib = CDLL(lib_path, mode=RTLD_GLOBAL)
	return ffi.dlopen(ffi.cast("void *", lib._handle))

[seberg]

Great cleanups, thanks! Adding black also is good.

[seberg]

Ah, nice thanks... That must have come from legate-df.