Updates node-sass version

[lunswor]

frontend_1  |     Module build failed: Error: Missing binding /django/node_modules/node-sass/vendor/linux-x64-48/binding.node
frontend_1  |     Node Sass could not find a binding for your current environment: Linux 64-bit with Node.js 6.x
frontend_1  |
frontend_1  |     Found bindings for the following environments:
frontend_1  |       - OS X 64-bit with Unsupported runtime (59)
frontend_1  |
frontend_1  |     This usually happens because your environment has changed since running `npm install`.
frontend_1  |     Run `npm rebuild node-sass --force` to build the binding for your current environment.