Unify domain validation regex to fix custom domain issues

app/Http/Controllers/CaddyController.php

@@ -2,6 +2,7 @@
 
 namespace App\Http\Controllers;
 
+use App\Http\Requests\Workspace\CustomDomainRequest;
 use App\Models\Workspace;
 use Illuminate\Http\Request;
 
@@ -14,7 +15,7 @@ class CaddyController extends Controller
         ]);
         // make sure domain is valid
         $domain = $request->input('domain');
-        if (!preg_match('/^[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}$/', $domain)) {
+        if (!preg_match(CustomDomainRequest::CUSTOM_DOMAINS_REGEX, $domain)) {
             return $this->error([
                 'success' => false,
                 'message' => 'Invalid domain',