chore(deps): update dependency optimize-css-assets-webpack-plugin to v6

Author: renovate-bot

package.json

@@ -43,7 +43,7 @@
     "babel-plugin-styled-components": "1.12.0",
     "css-loader": "2.1.1",
     "mini-css-extract-plugin": "0.12.0",
-    "optimize-css-assets-webpack-plugin": "5.0.6",
+    "optimize-css-assets-webpack-plugin": "6.0.0",
     "prop-types": "15.7.2",
     "terser-webpack-plugin": "1.4.5",
     "webpack": "4.46.0",