gh-134674: remove ast.MatchStar.name class-level default value

[hunterhogan]

Note prior pull requests

• In pull request gh-134674: fix: ast.MatchStar.name incorrectly having class-level default value #134676, I attempted to merge a branch based on 3.13 into main.
• I misunderstood the instructions from gh-134674: fix: ast.MatchStar.name incorrectly having class-level default value #134676, and attempted to backport merge to branch 3.13 in pull request [3.13] fix: remove ast.MatchStar.name class-level default value (gh-134674) #134681.

Changes to and compiled from branch main

Fixes gh-134674

Problem

ast.MatchStar.name incorrectly appears to have a class-level default value when using ast.dump(). The issue causes ast.MatchStar(name=None) to display as MatchStar() instead of the expected MatchStar(name=None).

Solution

Change the ASDL definition of MatchStar, and add MatchStar to the special cases list in ast.dump() alongside Constant and MatchSingleton.

[serhiy-storchaka]

This is not a correct change.