Update dependency postcss to v8.4.39

Author: renovate[bot]

package-lock.json

@@ -39,7 +39,7 @@
     "glob": "10.2.7",
     "handlebars": "4.7.7",
     "jquery": "3.7.0",
-    "postcss": "8.4.24",
+    "postcss": "8.4.39",
     "postcss-cli": "10.1.0",
     "request": "2.88.2",
     "sass": "1.63.3",