Replace MailManager singleton with an instance of a custom mail manager which always resolves the mailers instead of getting the cached ones

src/TenancyMailManager.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Stancl\Tenancy;
+
+use Illuminate\Mail\MailManager;
+
+class TenancyMailManager extends MailManager
+{
+    protected function get($name)
+    {
+        return $this->resolve($name);
+    }
+}