Fixes Stylelint issues

[kennethormandy]

Currently, there are two Stylelint errors, before any changes are made to the boilerplate:

• A dependency issue
• A linting error from a CSS file generated by the boilerplate

The first one appears to be a relatively recent dependency issue, which outputs “TypeError: opts.node.rangeBy is not a function”. Updating PostCSS, Stylelint, and the minimum version of Node v12.x seems to resolve this. bfe18fb

The second one is a linting error from the generated fonts.css file. It looks like the indentation and variable names generated by Specimen Skeleton Support don’t pass the formatting rules, so one option would be to fix it there. But since it is a build file, I figured it would work better to ignore it in the Stylelint config. bfe18fb

Thanks!

[RoelN]

@kennethormandy Apologies for leaving this lingering for so long, I completely missed this. Thanks for contributing and fixing the errors!