Data validation

[egpbos]

In #359, we started discussing data validation tools in Python: attrs (lightweight, convenient for value validation) and pydantic (use type hints for data type validation) were mentioned.

It seems convenient at least for configuration file handling, so in any case I think we should add it to the python chapter.

However, I'm wondering if it makes sense to discuss validation a bit more broadly in the data chapter. What useful experiences can we add from other perspectives? Are there similar packages in other languages worth mentioning?

[bouweandela]

Using a schema for validating configuration files could also be a good option.