Conformance - document Python 3.11 requirement for pytype tests

[Andrej730]

Not sure if it's still required-required by pytype - I haven't investigated, but wanted to document as it is the current conformance requirement.

Source:

typing/conformance/src/type_checker.py

Lines 313 to 318 in 0b9fed8

	def run_tests(self, test_files: Sequence[str]) -> dict[str, str]:
	# Specify 3.11 for now to work around the fact that pytype
	# currently doesn't support 3.12 and emits an error when
	# running on 3.12.
	options = pytype_config.Options.create(python_version=(3, 11), quick=True)
	loader = pytype_loader.create_loader(options)

[Andrej730]

Closing after #2010