Print the errors of the check_license.py

[psaiz]

trafficstars

Check the output of this action:

Run ./run-tests.sh --data-licenses
[INFO] Successfully validated file cms-trigger-information-2012.json
[INFO] Successfully validated file cms-pileup-datasets-2012.json
...
[INFO] Processed 3[28](https://github.com/cernopendata/opendata.cern.ch/actions/runs/14442278086/job/40494898258#step:4:29) files within 1.99 seconds.
Error:  Validation completed with 1 errors!
	Please ensure the licenses are one of the following: ['CC0-1.0', 'GPL-3.0-only', 'MIT', 'Apache-2.0', 'BSD-3-Clause'].
	If you are using a valid SPDX license string that is not in the above list, please contact `[email protected]`.
Error: Process completed with exit code 1.

It would be useful to have the ERROR messages fro the files that are not validated. In cases like invalid json, they just fail silently. I would also demote the [INFO] Successfully validated file .. to DEBUG level.