lib: fix extraneous space in module.js

An extra space was not caught by the linter due to what appears
to be a bug in eslint 4.3.0 — remove it.

PR-URL: https://github.com/nodejs/node/pull/16199


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>