Bump laravel-mix-purgecss from 4.2.0 to 5.0.0

Bumps [laravel-mix-purgecss](https://github.com/spatie/laravel-mix-purgecss) from 4.2.0 to 5.0.0.
- [Release notes](https://github.com/spatie/laravel-mix-purgecss/releases)
- [Changelog](https://github.com/spatie/laravel-mix-purgecss/blob/master/CHANGELOG.md)
- [Commits](https://github.com/spatie/laravel-mix-purgecss/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

package-lock.json

@@ -14,7 +14,7 @@
     "extra-watch-webpack-plugin": "^1.0.3",
     "hasbin": "^1.2.3",
     "laravel-mix": "^5.0.4",
-    "laravel-mix-purgecss": "^4.2.0",
+    "laravel-mix-purgecss": "^5.0.0",
     "node-cmd": "^3.0.0",
     "postcss-import": "^12.0.1",
     "tailwindcss": "^1.4.4",