Bump node-sass from 4.13.0 to 4.13.1

Bumps [node-sass](https://github.com/sass/node-sass) from 4.13.0 to 4.13.1.
- [Release notes](https://github.com/sass/node-sass/releases)
- [Changelog](https://github.com/sass/node-sass/blob/master/CHANGELOG.md)
- [Commits](sass/node-sass@v4.13.0...v4.13.1)

Signed-off-by: dependabot[bot] <support@github.com>

yarn.lock

@@ -4483,9 +4483,9 @@ node-pre-gyp@^0.12.0:
     tar "^4"
 
 node-sass@^4.13.0:
-  version "4.13.0"
-  resolved "https://registry.yarnpkg.com/node-sass/-/node-sass-4.13.0.tgz#b647288babdd6a1cb726de4545516b31f90da066"
-  integrity sha512-W1XBrvoJ1dy7VsvTAS5q1V45lREbTlZQqFbiHb3R3OTTCma0XBtuG6xZ6Z4506nR4lmHPTqVRwxT6KgtWC97CA==
+  version "4.13.1"
+  resolved "https://registry.yarnpkg.com/node-sass/-/node-sass-4.13.1.tgz#9db5689696bb2eec2c32b98bfea4c7a2e992d0a3"
+  integrity sha512-TTWFx+ZhyDx1Biiez2nB0L3YrCZ/8oHagaDalbuBSlqXgUPsdkUSzJsVxeDO9LtPB49+Fh3WQl3slABo6AotNw==
   dependencies:
     async-foreach "^0.1.3"
     chalk "^1.1.1"