node-sass 4.15 requires Node 14

[j2fong]

dcl-ui won't run with Node 16 and it has the following error,
`Syntax Error: Error: Node Sass does not yet support your current environment: OS X Unsupported architecture (arm64) with Unsupported runtime (93)
For more information on which environments are supported please see:
https://github.com/sass/node-sass/releases/tag/v4.14.1

@ ./src/assets/styles/layout.scss 4:14-235 15:3-20:5 16:22-243
@ ./src/main.js
@ multi (webpack)-dev-server/client?http://192.168.1.103:8080/&sockPath=/sockjs-node (webpack)/hot/dev-server.js ./src/main.js`

But it ran fine once I switched to node 14. Please update README to add the requirement of Node 14.