gh-138257: Fix internal RuleCollectorVisitor attribute name (#138208)

The internal `RuleCollectorVisitor` class had an attribute named "rulses"
instead of "rules" that other `GrammarVisitor` subclasses define.

Author: chemelnucfin

Tools/peg_generator/pegen/parser_generator.py

@@ -45,7 +45,7 @@ class RuleCollectorVisitor(GrammarVisitor):
     """Visitor that invokes a provided callmaker visitor with just the NamedItem nodes"""
 
     def __init__(self, rules: Dict[str, Rule], callmakervisitor: GrammarVisitor) -> None:
-        self.rulses = rules
+        self.rules = rules
         self.callmaker = callmakervisitor
 
     def visit_Rule(self, rule: Rule) -> None: