FIX allow any laravel mix version as peer dependency

Author: riccardodallavia

package.json

@@ -19,7 +19,7 @@
   },
   "homepage": "https://github.com/maize-tech/laravel-mix-static-cache-busting#readme",
   "peerDependencies": {
-    "laravel-mix": "^5.0.1"
+    "laravel-mix": "*"
   },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"