Merge branch 'update_gulp_sass' into 'master'

Update gulp-sass to get node-sass 4.13 which works with current ddev containers

Closes #628

See merge request t3o/t3olayout!579

Build/package.json

@@ -35,7 +35,7 @@
     "gulp-file-include": "^2.0.1",
     "gulp-plumber": "^1.2.0",
     "gulp-rename": "^1.2.2",
-    "gulp-sass": "^4.0.1",
+    "gulp-sass": "^4.0.2",
     "gulp-sourcemaps": "^2.6.3",
     "gulp-stylefmt": "^1.1.0",
     "gulp-stylelint": "^6.0.0",