adding spaces in pseudo selectors causing errors for gulp sass

codeFormatter is setting these elements like this:
`span: not(: last-child) {`

Which causes an issue when compiling the css files.

Error from terminal
```
Error: Invalid CSS after " span: not(": expected expression (e.g. 1px, bold), was ": last-child) {"
on line 144 of source/stylesheets/modules/_grid.scss
>> span: not(: last-child) {
------------^
```