Deprecation warnings with Python 3.12

Running the inkex (from Inkscape 1.3.2) test suite on NixOS shows the following warnings:

inkex/tester/inx.py:157
  /build/inkscape-1.3.2_2023-11-25_091e20ef0f/share/extensions/inkex/tester/inx.py:157: DeprecationWarning: contents is deprecated. Use files() instead. Refer to https://importlib-resources.readthedocs.io/en/latest/using.html#migrating-from-legacy for migration advice.
    for name in resources.contents(__package__):

inkex/tester/inx.py:163
  /build/inkscape-1.3.2_2023-11-25_091e20ef0f/share/extensions/inkex/tester/inx.py:163: DeprecationWarning: open_binary is deprecated. Use files() instead. Refer to https://importlib-resources.readthedocs.io/en/latest/using.html#migrating-from-legacy for migration advice.
    with resources.open_binary(__package__, name) as fp:

tests/test_color_custom.py: 35 warnings
  /build/inkscape-1.3.2_2023-11-25_091e20ef0f/share/extensions/color_custom.py:32: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    if isinstance(node, ast.Num):  # <number>

tests/test_color_custom.py::ColorCustomTest::test_colors
tests/test_color_custom.py::ColorCustomTest::test_colors
tests/test_color_custom.py::ColorCustomTest::test_colors
tests/test_color_custom.py::ColorCustomTest::test_colors
tests/test_color_custom.py::ColorCustomTest::test_colors
tests/test_color_custom.py::ColorCustomTest::test_colors
  /build/inkscape-1.3.2_2023-11-25_091e20ef0f/share/extensions/color_custom.py:33: DeprecationWarning: Attribute n is deprecated and will be removed in Python 3.14; use value instead
    return node.n

The first two were probably fixed by 629c79f6 but the latter two are still there on master:

https://gitlab.com/inkscape/extensions/-/blob/d3ef8eae3e1c9635fff8d6286801ae779950a7c4/color_custom.py#L32

https://gitlab.com/inkscape/extensions/-/blob/d3ef8eae3e1c9635fff8d6286801ae779950a7c4/color_custom.py#L33