allow wider range of pandas queries

[EricRLucas]

I've been trying to pass queries to the malariagen_data functions that are more complex than checking for equality (eg: checking whether the taxon field contains the word "coluzzii"). This is possible for a pandas df by using str.contains or str.match, and adding the 'engine == "python"' argument, to the query call, but as far as I can't tell this can't be passed to the malariagen_data function. Would be useful to be able to pass regex queries to the data.