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/5.0.0)

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

Author: dependabot[bot]

package-lock.json

@@ -20,7 +20,7 @@
         "extra-watch-webpack-plugin": "^1.0.3",
         "hasbin": "^1.2.3",
         "laravel-mix": "^5.0.7",
-        "laravel-mix-purgecss": "^4.2.0",
+        "laravel-mix-purgecss": "^5.0.0",
         "lodash": "^4.17.20",
         "node-cmd": "^3.0.0",
         "sass": "^1.26.11",