chore(package): update optimize-css-assets-webpack-plugin to version 5.0.3

Closes #76

Author: greenkeeper[bot]

package.json

@@ -75,7 +75,7 @@
     "jest": "^23.6.0",
     "jest-serializer-vue": "^2.0.0",
     "node-notifier": "^5.1.2",
-    "optimize-css-assets-webpack-plugin": "^4.0.2",
+    "optimize-css-assets-webpack-plugin": "^5.0.3",
     "ora": "^2.1.0",
     "portfinder": "^1.0.13",
     "postcss-import": "^11.0.0",