packagedcode: don't use removed ast module attributes

[gotmax23]

This is needed for Python 3.14 compatibility.

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[pombredanne]

Thanks. Is the logic really the same?

[pombredanne]

The logic is now different, is it?
if isinstance(statement_v, (ast.Str, ast.Constant)): would kick in on either of ast.Str or ast.Constant but now it only kicks in with ast.Constant with a string value?