tools: fix typo in .eslintrc.js

Refs: https://github.com/nodejs/node/pull/18566

PR-URL: https://github.com/nodejs/node/pull/21449


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>