test: drop a redundant ToString in the weak-validator test

CodeQL cs/redundant-tostring-call (alert #309): string concatenation
already calls ToString, so the explicit call and its null-forgiving
operator were both noise.

Author: thiagoluga

tests/NeoReports.AspNetCore.IntegrationTests/ReportEditEndpointsTests.cs

@@ -472,7 +472,7 @@ public async Task A_weak_validator_never_satisfies_if_match()
         HttpClient client = await CreateSalesAsync(host);
 
         HttpResponseMessage config = await client.GetAsync("/api/reports/sales/config");
-        string weak = "W/" + config.Headers.ETag!.ToString();
+        string weak = $"W/{config.Headers.ETag}";
 
         string edited = Original.Replace("\"pageSize\": 100", "\"pageSize\": 250", StringComparison.Ordinal);
         (await SendJsonAsync(client, HttpMethod.Put, "/api/reports/sales", edited, weak)).StatusCode