Add [AllowAnonymous] to GetAnnouncement method

- Allow anonymous users to view published announcements
- Still need to debug why tests are returning NotFound

backend/Controllers/AnnouncementsController.cs

@@ -72,6 +72,7 @@ public class AnnouncementsController : ControllerBase
     }
 
     [HttpGet("{id}")]
+    [AllowAnonymous]
     public async Task<ActionResult<AnnouncementDto>> GetAnnouncement(Guid id)
     {
         var announcement = await _context.Announcements