Python AST deprecations

[akaihola]

In my CI build, I'm getting these deprecation warnings from Python 3.12:

  lib/python3.12/site-packages/astor/op_util.py:92: DeprecationWarning:
    ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    precedence_data = dict((getattr(ast, x, None), z) for x, y, z in op_data)

  lib/python3.12/site-packages/flynt/utils/utils.py:74: DeprecationWarning:
    ast.Str is deprecated and will be removed in Python 3.14; use ast.Constant instead
    ) -> Union[ast.FormattedValue, ast.Str]:

  lib/python3.12/site-packages/flynt/transform/format_call_transforms.py:22: DeprecationWarning:
    Attribute s is deprecated and will be removed in Python 3.14; use value instead
    string = fmt_call.func.value.s

  lib/python3.12/ast.py:407: DeprecationWarning:
    visit_Str is deprecated; add visit_Constant
    return visitor(node)

[ikamensh]

Thanks for reporting!
hm, it seems ast.Str and ast.Num and perhaps other nodes will be all merged into ast.Constant. Naively replacing ast.Str with ast.Constant leads to errors in flynt.

Unfortunately I couldn't find a solution to suppress these warnings either, they are no issue for users until they start using python3.14, so if I could I'd just supress warnings until then.