Update dependency postcss to v8.5.4

Author: renovate[bot]

package-lock.json

@@ -26,7 +26,7 @@
     "html-webpack-plugin": "5.6.3",
     "mini-css-extract-plugin": "2.9.2",
     "monaco-editor-webpack-plugin": "7.1.0",
-    "postcss": "8.5.3",
+    "postcss": "8.5.4",
     "postcss-loader": "8.1.1",
     "sass": "1.89.0",
     "sass-loader": "16.0.5",