Added slugify package to config

Author: danurbanowicz

.eleventy.js

@@ -2,6 +2,7 @@ const { DateTime } = require("luxon");
 const CleanCSS = require("clean-css");
 const UglifyJS = require("uglify-es");
 const htmlmin = require("html-minifier");
+const slugify = require("slugify");
 const eleventyNavigationPlugin = require("@11ty/eleventy-navigation");
 
 module.exports = function(eleventyConfig) {