eslint-plugin-compat requires a peer of eslint but none is installed

[unguul]

Running npm install after pulling from git prints the following:

npm WARN [email protected] requires a peer of eslint@^3.0.0 || ^4.0.0 || ^5.0.0 || ^6.0.0 but none is installed. You must install peer dependencies yourself.

Running npm install eslint makes the warning go away so perhaps we could add eslint as a dependency in package.json?