minor #13455 Namespace import reference missing (zspine)

This PR was squashed before being merged into the 5.0 branch (closes #13455).

Discussion
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Namespace import reference missing

I forgot to add the Route annotation import

```
use Symfony\Component\Routing\Annotation\Route;
```

Commits
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877d031 Namespace import reference missing

Author: javiereguiluz

notifier/texters.rst

@@ -14,6 +14,10 @@ you to send SMS messages::
 
     // src/Controller/SecurityController.php
     namespace App\Controller;
+    
+    use Symfony\Component\Notifier\Message\SmsMessage;
+    use Symfony\Component\Notifier\TexterInterface;
+    use Symfony\Component\Routing\Annotation\Route;
 
     class SecurityController
     {