Data type integration test with (almost) all datatypes in Polars

[vankesteren]

I think we should create a debug dataset which includes all (or all relevant) data types in Polars. The debug dataset can be included in the demo files.

This can become the basis for an integration test (as previously mentioned in #270). The integration test should perform all steps in the pipeline and check whether the data types are appropriately reproduced.

[qubixes]

Maybe it makes more sense to have a dataset repository, where we can keep adding more datasets (from the wild) to test? Or do you prefer it to be integrated into the main repository?