Don't attach row names during subsetting

[LTLA]

BiocFrame/src/biocframe/BiocFrame.py

Lines 490 to 492 in e9f56ff

	temp_row_names = self.row_names
	if temp_row_names is None:
	temp_row_names = list(range(self.shape[0]))

should not exist, I shouldn't see magic row names appear after slicing.