Remove EF query warnings from test runs

Endpoints/ResultsWorkflowService.cs

@@ -9,7 +9,7 @@ internal sealed class ResultsWorkflowService(AppDbContext db)
 {
     public async Task<IResult> GetResultsAsync(Guid playerId)
     {
-        var appState = await db.AppState.AsNoTracking().FirstAsync();
+        var appState = await db.AppState.AsNoTracking().SingleAsync();
         if (!appState.ResultsOpen)
             return EndpointHelpers.BadRequestError("Results are locked until the admin enables them.");