site: Bump gulp-sass from 4.0.2 to 5.1.0 and add sass (fixes #882)

Author: vorburger

site/gulpfile.js

@@ -13,7 +13,7 @@ const htmlmin = require('gulp-htmlmin');
 const merge = require('merge-stream');
 const postcss = require('gulp-html-postcss');
 const rename = require('gulp-rename');
-const sass = require('gulp-sass');
+const sass = require('gulp-sass')(require('sass'));
 const through = require('through2');
 const useref = require('gulp-useref');
 const vulcanize = require('gulp-vulcanize');

site/package.json

@@ -21,7 +21,7 @@
     "gulp-ignore": "^2.0.2",
     "gulp-rename": "^1.4.0",
     "gulp-replace": "^1.0.0",
-    "gulp-sass": "^4.0.2",
+    "gulp-sass": "^5.1.0",
     "gulp-uglify": "^3.0.1",
     "gulp-useref": "^3.1.6",
     "gulp-vulcanize": "^7.0.0",
@@ -33,6 +33,7 @@
     "merge-stream": "^1.0.1",
     "path": "^0.12.7",
     "postcss-syntax": "^0.34.0",
+    "sass": "^1.69.5",
     "swig-templates": "^2.0.3",
     "through2": "^3.0.0",
     "uglify-es": "^3.3.9",