chore: remove legacy check command and distutils (#233)

The `check` command was ported to `twine check` in 2018.
Refs: #122

Python 3.10 and 3.11 have marked `distutils` as deprecated.
Refs: https://peps.python.org/pep-0632/#specification

Signed-off-by: Mike Fiedler <[email protected]>

Author: miketheman

readme_renderer/integration/__init__.py

@@ -58,9 +58,6 @@
     ],
     install_requires=["bleach>=2.1.0", "docutils>=0.13.1", "Pygments>=2.5.1"],
     include_package_data=True,
-    entry_points={
-        "distutils.commands": ["check = readme_renderer.integration.distutils:Check"],
-    },
     extras_require={"md": "cmarkgfm>=0.8.0"},
     packages=setuptools.find_packages(exclude=["tests", "tests.*"]),
     python_requires=">=3.6",