tools: update ESLint to 6.7.1

Update ESLint to 6.7.1

PR-URL: https://github.com/nodejs/node/pull/30598


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>