Bump to node-sass@^4.7.2

[ricardocasares]

This provides a workaround to test case when an included mixin is called inside an standalone mixin.

[rootical]

Oh we need this actually as well... Thanks for the PR, @ricardocasares

[ricardocasares]

@ryanbahniuk any comments on this?

[ryanbahniuk]

Is the bump to node-sass 4.7.2 required for this feature change?

[ricardocasares]

@actually we just needed to update node-sass, but there is one test that fails on 4.7.2 because of #2245. Apparently, before it was possible to compile an included mixin even though the output was incorrect, ie: running @include appearance(none) outside any selectors, would not produce valid css.

Now node-sass is throwing this error, thus the test fails.

[alazurenko]

Would be great to have updated version of node-sass 🙂
What do you think @ryanbahniuk?