Fix copy-paste error in Tools/clinic.py

[sobolevn]

While working on #100550 I've noticed that there's a copy-pasted phrase from

cpython/Tools/clinic/clinic.py

Lines 2819 to 2833 in b0ea289

	def initialize(self):
	"""
	The C statements required to set up this variable before parsing.
	Returns a string containing this code indented at column 0.
	If no initialization is necessary, returns an empty string.
	"""
	return ""
	def modify(self):
	"""
	The C statements required to modify this variable after parsing.
	Returns a string containing this code indented at column 0.
	If no initialization is necessary, returns an empty string.
	"""
	return ""

Skipping news and issue for a trivial change.