Update dependency postcss to v8.4.29

Author: renovate[bot]

package-lock.json

@@ -26,7 +26,7 @@
     "css-loader": "6.8.1",
     "html-webpack-plugin": "5.5.3",
     "mini-css-extract-plugin": "2.7.6",
-    "postcss": "8.4.28",
+    "postcss": "8.4.29",
     "postcss-loader": "7.3.3",
     "sass": "1.66.1",
     "sass-loader": "13.3.2",