fix: count in retries

Author: PJEstrada

sdk/diffgram/core/diffgram_dataset_iterator.py

@@ -53,7 +53,7 @@ def get_image_data(self, diffgram_file):
                     image = imread(diffgram_file.image.get('url_signed'))
                     break
                 except Exception as e:
-                    if i < MAX_RETRIES:
+                    if i < MAX_RETRIES - 1:
                         continue
                     else:
                         raise e