Seems tomli was upgraded to v2.0.1 (autogen'd and required by setuptools). I get this error when installing upgrading dev-python/botocore:

 * python3_7: running distutils-r1_run_phase distutils-r1_python_compile
python3.7 setup.py build -j 8
/usr/lib/python3.7/site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'build-base' will not be supported in future versions. Please use the underscore name 'build_base' instead
  % (opt, underscore_opt)
/usr/lib/python3.7/site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'build-platlib' will not be supported in future versions. Please use the underscore name 'build_platlib' instead
  % (opt, underscore_opt)
/usr/lib/python3.7/site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'build-purelib' will not be supported in future versions. Please use the underscore name 'build_purelib' instead
  % (opt, underscore_opt)
/usr/lib/python3.7/site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'build-scripts' will not be supported in future versions. Please use the underscore name 'build_scripts' instead
  % (opt, underscore_opt)
/usr/lib/python3.7/site-packages/setuptools/dist.py:726: UserWarning: Usage of dash-separated 'dist-dir' will not be supported in future versions. Please use the underscore name 'dist_dir' instead
  % (opt, underscore_opt)
Traceback (most recent call last):
  File "setup.py", line 59, in <module>
    'Programming Language :: Python :: 3.10',
  File "/usr/lib/python3.7/site-packages/setuptools/{}init{}.py", line 153, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib/python3.7/distutils/core.py", line 108, in setup
    _setup_distribution = dist = klass(attrs)
  File "/usr/lib/python3.7/site-packages/setuptools/dist.py", line 463, in {}init{}
    for k, v in attrs.items()
  File "/usr/lib/python3.7/distutils/dist.py", line 292, in {}init{}
    self.finalize_options()
  File "/usr/lib/python3.7/site-packages/setuptools/dist.py", line 837, in finalize_options
    ep(self)
  File "/usr/lib/python3.7/site-packages/setuptools_scm/integration.py", line 100, in infer_version
    config = Configuration.from_file(dist_name=dist_name)
  File "/usr/lib/python3.7/site-packages/setuptools_scm/config.py", line 196, in from_file
    defn = _load_toml(data)
  File "/usr/lib/python3.7/site-packages/setuptools_scm/config.py", line 59, in _lazy_tomli_load
    from tomli import loads
ModuleNotFoundError: No module named 'tomli'
{{}}

 * ERROR: dev-python/botocore-1.23.51::python-modules-kit failed (compile phase):