Update node-sass

[desrosj]

Running npm install currently fails when running the latest version of Node (12.2.0 with NPM 6.9.0).

The repo currently requires ~4.11.0 of node-sass, but only 4.12+ supports Node 12.2.0.

[desrosj]

Opened an accompanying ticket for Core.

[aduth]

This was discussed during today's #core-js chat (link requires registration):

https://wordpress.slack.com/archives/C5UNMSU4R/p1557843578353500

Noted there that technically the project doesn't support Node 12.x yet. That being said, this seems like a reasonable and non-conflicting change, with the added benefit of improved future compatibility.

You should be running a Node version matching the current active LTS release or newer for this plugin to work correctly.

https://github.com/WordPress/gutenberg/blob/master/docs/contributors/getting-started.md

12.x […] Active LTS Start: 2019-10-22

https://github.com/nodejs/Release#release-schedule

[swissspidy]

There was similar discussion previously when I opened #12539 / #12541, but in the end it was merged without any issues. I don't see any downsides to this change now either.

[aduth]

Looks good 👍 Tested successfully both in Node 10.15.3 (active LTS) and Node 12.2.0.