Duration properties not properly parsed

[hexylena]

Describe the bug

I see the following error message:

For property:timeRequired , 'PT2H30M' is not valid under any of the given schemas
We are expecting "Duration" in an array or as a single object

however that is a valid ISO8601 time spec: https://schema.org/Duration

https://schema.org/timeRequired shows an example that's essentially the same (PT1H)

To Reproduce
Steps to reproduce the behavior:

1. python src/command.py validate --target_data=https://training.galaxyproject.org/training-material/topics/admin/tutorials/ansible-galaxy/tutorial.html --static_jsonld