Update gulp-sass to work on new Mac OS version

package.json

@@ -38,7 +38,7 @@
     "gulp-rename": "^1.2.2",
     "gulp-rev-timestamp": "0.0.1",
     "gulp-rsync": "0.0.7",
-    "gulp-sass": "^2.1.0",
+    "gulp-sass": "^3.2.1",
     "gulp-sass-lint": "^1.3.2",
     "gulp-sourcemaps": "^1.6.0",
     "gulp-strip-css-comments": "^1.2.0",