Resolve TODO for distutils migration as not applicable

[codesue]

What does this pull request do?

Resolves the TODO to migrate setup.py from distutils to setuptools since it's not applicable. There isn't a good setuptools alternative yet for distutils.command.build, and we can continue to use distutils through setuptools' bundled copy after it's removed from the standard library. See pypa/setuptools#2928.

Fixes #269

How did you test this change?

n/a

How did you document this change?

n/a

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[rcrowe-google]

Thanks!