Update prompts.py

prompts.py

@@ -9,7 +9,7 @@ system_prompt_template = """
     5. Don't interpolate or make up data.
     6. Please maintain the table structure of the charges, i.e., capture all of the rows and columns in the JSON object.
     7. Return null if the data is not available.
-    8. If no checkboxes are selected, just return null.
+    8. If no checkboxes are selected, just return null not "null" as string.
     9. Triple check any numbers provided in the attached image.
     10. Properly check which row the data belongs to.