fix CP2K TaskDocument

[lory-w]

Summary

This PR addresses the ValidationError occurring in the TaskDocument schema due to improper handling of the cp2k_input and locpot fields. This issue is documented in issue #899

• Changed cp2k_input in CalculationInput to be a union of CP2KInput object and dict to accommodate different possible types for cp2k_input
• Changed locpot in CalculationOutput to be an optional field

[JaGeo]

@lory-w thank you! Is there a chance that you could add a test as well?

[lory-w]

Hi,
Thank you for reviewing the PR. I attempted to write a pytest but the error only occurs when the calculation results are queried by Jobflow from Store (in my case mongodb). However, the current test suite in the repo does not seem to have integration with mongodb, so I cannot reproduce the bug within the unit tests.

Would you suggest any specific approach to handle this? Thanks!

[JaGeo]

@utf maybe you could have a look once you have time!

[utf]

I will look into the jobflow issue but will merge this for the time being.