False positive invalid condition ID.

Which problem would you like to address? Please describe.
Linting complains about invalid condition IDs. I believe the error is due to the fact that the condition id is numeric only. Ideally the error would be a bit more informative what the actual issue is with the condition ID.

Describe the solution you would like
Change the spec to be more accurate about identifier restrictions or change linting to be more permissive about identifiers.

Describe alternatives you have considered
Don't use numbers in identifiers.

Additional context
Can be checked via check_condition_df(pd.DataFrame({petab.CONDITION_ID: ['0']}).set_index(petab.CONDITION_ID), None).

Not sure how much sense it makes to print line numbers when operating with a DataFrame.

Typehints in check_condition_df are inconsistent with the function signature, i.e., sbml_model is not and optional argument.