feat: upgrade optimize-css-assets-webpack-plugin to 5.0.4

closes #506

Author: jlengrand

package.json

@@ -47,7 +47,7 @@
     "mini-css-extract-plugin": "0.12.0",
     "minimist": "1.2.5",
     "object-assign": "4.1.1",
-    "optimize-css-assets-webpack-plugin": "5.0.3",
+    "optimize-css-assets-webpack-plugin": "5.0.4",
     "postcss-flexbugs-fixes": "4.2.1",
     "postcss-loader": "4.0.3",
     "postcss-safe-parser": "5.0.2",