Remove depreciation warnings from tests for python 3.7 features

[gordonwatts]

Currently there are a few depreciation warnings that it would be nice to get rid of if we didn't have to also support 3.7:

============================== warnings summary ===============================
func_adl/ast/function_simplifier.py:436
  /home/runner/work/func_adl/func_adl/func_adl/ast/function_simplifier.py:436: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    def visit_Subscript_Tuple(self, v: ast.Tuple, s: Union[ast.Num, ast.Constant, ast.Index]):

func_adl/ast/function_simplifier.py:566
  /home/runner/work/func_adl/func_adl/func_adl/ast/function_simplifier.py:566: DeprecationWarning: ast.Str is deprecated and will be removed in Python 3.14; use ast.Constant instead
    def _get_value_from_index(arg: Union[ast.Num, ast.Constant, ast.Index, ast.Str]) -> Optional[int]:

tests/test_event_dataset.py::test_eds_recovery_no_root
tests/test_event_dataset.py::test_eds_recovery_no_root
  /home/runner/work/func_adl/func_adl/tests/test_event_dataset.py:69: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    q = ObjectStream(ast.BinOp(ast.Num(1), ast.Add, ast.Num(2)))

tests/test_object_stream.py::test_simple_query
  /opt/hostedtoolcache/Python/3.12.0/x64/lib/python3.12/site-packages/make_it_sync/func_wrapper.py:10: DeprecationWarning: There is no current event loop
    loop = asyncio.get_event_loop()

tests/test_util_ast.py: 4 warnings
tests/ast/test_function_simplifier.py: 7 warnings
  /home/runner/work/func_adl/func_adl/func_adl/util_ast.py:265: DeprecationWarning: ast.NameConstant is deprecated and will be removed in Python 3.14; use ast.Constant instead
    if not isinstance(rl.body, ast.NameConstant):

tests/ast/test_func_adl_ast_utils.py::test_node_transform_function_ast_with_object_args
  /home/runner/work/func_adl/func_adl/tests/ast/test_func_adl_ast_utils.py:66: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    assert isinstance(e.args[0], ast.Num)

tests/ast/test_func_adl_ast_utils.py::test_node_transform_function_ast_with_object_args
  /home/runner/work/func_adl/func_adl/tests/ast/test_func_adl_ast_utils.py:67: DeprecationWarning: Attribute n is deprecated and will be removed in Python 3.14; use value instead
    assert e.args[0].n == 10

tests/ast/test_func_adl_ast_utils.py::test_node_visit_function_ast_with_object_args
  /home/runner/work/func_adl/func_adl/tests/ast/test_func_adl_ast_utils.py:172: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    assert isinstance(e.args[0], ast.Num)

tests/ast/test_func_adl_ast_utils.py::test_node_visit_function_ast_with_object_args
  /home/runner/work/func_adl/func_adl/tests/ast/test_func_adl_ast_utils.py:173: DeprecationWarning: Attribute n is deprecated and will be removed in Python 3.14; use value instead
    assert e.args[0].n == 10

tests/ast/test_function_simplifier.py: 15 warnings
  /home/runner/work/func_adl/func_adl/func_adl/ast/function_simplifier.py:576: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    if isinstance(a, ast.Num):

tests/ast/test_function_simplifier.py: 10 warnings
  /home/runner/work/func_adl/func_adl/func_adl/ast/function_simplifier.py:577: DeprecationWarning: Attribute n is deprecated and will be removed in Python 3.14; use value instead
    return cast(int, a.n)

tests/ast/test_function_simplifier.py::test_dict_select_reference
tests/ast/test_function_simplifier.py::test_dict_select_index
tests/ast/test_function_simplifier.py::test_dict_in_lambda
tests/ast/test_function_simplifier.py::test_dict_around_first
  /home/runner/work/func_adl/func_adl/func_adl/ast/function_simplifier.py:483: DeprecationWarning: ast.Str is deprecated and will be removed in Python 3.14; use ast.Constant instead
    assert isinstance(value, (ast.Str, ast.Constant, ast.Num))