expr_text is removed

With bpo-37050, expr_text field of FormattedValue has been removed. This part is now unnecessary

Lines 604 to 607 in c7553c7

    
           # expr_text used for f-string debugging syntax. 
        
           if getattr(value, 'expr_text', None): 
        
               self.write(value.expr_text) 
        
           else:

	# expr_text used for f-string debugging syntax.
	if getattr(value, 'expr_text', None):
	self.write(value.expr_text)
	else: