Setting validation with data-type fails

When runnign 
```
./ontrack-cli validate --project project-name --branch release-1.0.0 --build 1 --validation new  \
   --data-type net.nemerosa.ontrack.extension.general.validation.TestSummaryValidationDataType \
   --data {passed: 1, skipped: 2, failed: 3}
```
We get an error:
```
Error: invalid character 'p' looking for beginning of object key string
```