Fix deprecated warnings
```
tests/test_cli.py: 25 warnings
  /home/build/py2many/py2many/inference.py:62: DeprecationWarning: ast.NameConstant is deprecated and will be removed in Python 3.14; use ast.Constant instead
    elif isinstance(node, ast.Constant) or isinstance(node, ast.NameConstant):

  /home/build/py2many/py2many/rewriters.py:517: DeprecationWarning: Assign.__init__ got an unexpected keyword argument 'scopes'. Support for arbitrary keyword arguments is deprecated and will be removed in Python 3.15.
    assign = ast.Assign(

  /home/build/py2many/pycpp/transpiler.py:538: DeprecationWarning: ast.Ellipsis is deprecated and will be removed in Python 3.14; use ast.Constant instead
    if isinstance(node.slice, ast.Ellipsis):
    ```