Replace obsolete promisify

Author: FND

lib/make-postcss.js

@@ -1,8 +1,7 @@
 let postcss = require("postcss");
 let atImport = require("postcss-import");
 let assetURL = require("./asset-url");
-let { promisify } = require("faucet-pipeline-core/lib/util");
-let readFile = promisify(require("fs").readFile);
+let { readFile } = require("node:fs/promises");
 
 module.exports = function(input, target, assetManager, sourcemaps, browsers, compact) {
 	let plugins = [