Performance improvements

Breaking change

• Bumped Node.js to v14.eslint-plugin-diff will probably still work with Node.js v12, but it's not officially supported anymore.

What's Changed

• Add --no-ext-diff to git diff commands by @flupke in #23

New Contributors

• @flupke made their first contribution in #23

Full Changelog: v1.0.15...v2.0.0