Update dependency optimize-css-assets-webpack-plugin to v5.0.6

Author: renovate-bot

package.json

@@ -130,7 +130,7 @@
     "webpack": "4.46.0",
     "webpack-cli": "3.3.12",
     "webpack-dev-server": "3.11.2",
-    "optimize-css-assets-webpack-plugin": "5.0.4",
+    "optimize-css-assets-webpack-plugin": "5.0.6",
     "terser-webpack-plugin": "4.2.3",
     "webpack-merge": "4.2.2"
   }