Rate-limited API request retries are canceled immediately

SlackNet/SlackApiClient.cs

@@ -246,7 +246,7 @@ private async Task<T> WebApiRequest<T>(Func<HttpRequestMessage> createRequest, C
             }
             catch (SlackRateLimitException e) when (!DisableRetryOnRateLimit)
             {
-                await Task.Delay(e.RetryAfter ?? TimeSpan.FromSeconds(1)).ConfigureAwait(false);
+                await Task.Delay(e.RetryAfter ?? TimeSpan.FromSeconds(1), cancellationToken ?? CancellationToken.None).ConfigureAwait(false);
             }
         }
     }