Sarcpdo Experiments Failing Validation

There is one row (21) with a missing `improve_drug_id` value in the experiments file. Not sure if this came from a change in the data or what.


```
2025-08-02 10:44:58 [ERROR] [/tmp/sarcpdo_experiments.tsv/21] 'improve_drug_id' is a required property in /
```