stop using deprecated setuptools.command.test

[nazimisik]

resolves #138

[cgtobi]

@nazimisik Thanks, this solves the issue for me.

[wimglenn]

@chaimleib 2024-Nov-15 is coming up soon, there are only a couple of weeks left to fix this issue:

$ pip install intervaltree
Resolved 2 packages in 2ms
error: Failed to prepare distributions
  Caused by: Failed to download and build `intervaltree==3.1.0`
  Caused by: Build backend failed to determine requirements with `build_wheel()` (exit status: 1)

[stderr]
Traceback (most recent call last):
  File "<string>", line 14, in <module>
    requires = get_requires_for_build({})
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/build_meta.py", line 333, in get_requires_for_build_wheel
    return self._get_build_requires(config_settings, requirements=[])
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/build_meta.py", line 303, in _get_build_requires
    self.run_setup()
    ~~~~~~~~~~~~~~^^
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/build_meta.py", line 521, in run_setup
    super().run_setup(setup_script=setup_script)
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/build_meta.py", line 319, in run_setup
    exec(code, locals())
    ~~~~^^^^^^^^^^^^^^^^
  File "<string>", line 32, in <module>
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/command/test.py", line 10, in __getattr__
    SetuptoolsDeprecationWarning.emit(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        "The test command is disabled and references to it are deprecated.",
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        stacklevel=2,
        ^^^^^^^^^^^^^
    )
    ^
  File "/Users/wim/.cache/uv/builds-v0/.tmpvDRuNi/lib/python3.13/site-packages/setuptools/warnings.py", line 52, in emit
    warnings.warn(text, cls, stacklevel=stacklevel + 1)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
setuptools.warnings.SetuptoolsDeprecationWarning: The test command is disabled and references to it are deprecated.
!!

        ********************************************************************************
        Please remove any references to `setuptools.command.test` in all supported versions of the affected package.

        By 2024-Nov-15, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.
        ********************************************************************************

!!