Update dependency purgecss-webpack-plugin to v7

ui/package.json

@@ -10,7 +10,7 @@
     "glob": "11.0.0",
     "html-webpack-plugin": "5.6.3",
     "mini-css-extract-plugin": "2.9.2",
-    "purgecss-webpack-plugin": "6.0.0",
+    "purgecss-webpack-plugin": "7.0.2",
     "webpack": "latest",
     "webpack-cli": "latest",
     "webpack-subresource-integrity": "5.1.0"