build: revert all attempts to disable docs travis-ci will remain broken for nightly (3.12) testing. Trying to enable maintainer mode broke on a missing dot executable. Disable nightly since something is borked in the base config there and I don't want to waste credits on it.

from roundup.dist.command.build import build_message_files, check_manifest
from setuptools.command.install_lib import install_lib as base

class install_lib(base):

    def run(self):
        check_manifest()
        build_message_files(self)
        base.run(self)