calcs/risk:

Fixed a couple of calls to risklib's `scientific.conditional_loss_ratio`, to
match the new interface.
calcs/risk/general:

Added some more validation checks to `parse_vulnerability_model`.
tests/calcs/risk/general_test:

Directly test a few invalid vulnerability model cases.
tests/data/end-to-end-hazard-risk/vulnerability_model.xml:

Fixed CoV values so that this demo doesn't crash.