refactor(Application): Aufrüstung von Core.Client auf 2.0.1

EnvelopeGenerator.Web/Controllers/Test/TestMessagingController.cs

@@ -14,6 +14,7 @@ namespace EnvelopeGenerator.Web.Controllers.Test
             _service = service;
         }
 
+        [HttpPost]
         public async Task<IActionResult> SendAsync(string recipient, string message)
         {
             await _service.SendSmsAsync(recipient: recipient, message: message);