feat: add last month date range to statistics in HomeController

Added a new date range for "Last Month" in the statistics filters of the HomeController, enhancing the data analysis capabilities for users.

app/Http/Controllers/Admin/HomeController.php

@@ -57,6 +57,7 @@ public function index(Request $request): View
             now()->subDays(7)->format('Y-m-d') => 'Les 7 derniers jours',
             now()->subDays(30)->format('Y-m-d') => 'Les 30 derniers jours',
             now()->startOfMonth()->format('Y-m-d') => 'Ce mois-ci',
+            now()->subMonth()->startOfMonth()->format('Y-m-d') => 'Le mois dernier',
         ];
 
         if ($visits->isNotEmpty()) {