Fix two labels back to back

If you check something like doc 12483 in the competition, you'll see that the tokens and labels are back-to-back

```
('B-NAME_STUDENT', 'Lamiaa'),
('I-NAME_STUDENT', 'Achraf'),
('B-ID_NUM', 'Weyhacy_7000693584')
```

The gradio app will label them both as ID_NUM.


This PR should fix that and not have any other issues.

app.py

@@ -86,7 +86,7 @@ def render_sample(subset, pii_type):
     for index, label in enumerate(sample['labels']):
         if label.startswith('B-'):
             if in_entity:  # End the previous entity
-                ents.append(Span(doc, start, end, label[2:]))
+                ents.append(Span(doc, start, end, sample['labels'][start][2:]))
             start, end = index, index + 1  # Start a new entity
             in_entity = True
         elif label.startswith('I-') and in_entity: