refactor: Replace postcss-purgecss import statement

postcss.config.js

@@ -1,4 +1,4 @@
-const purgecss = require("postcss-purgecss")({
+const purgecss = require("@fullhuman/postcss-purgecss")({
   content: ["./hugo_stats.json"],
   defaultExtractor: (content) => {
     let els = JSON.parse(content).htmlElements;