bloodhunter: Fix patron for Order of the Profane Soul

[PJBrs]

The Bloodhunter Feature Selector for OtherwordlyPatron lists the options for the patron choices capitalised. However, the code in FeatureSelector expects them to be lowercased. Make the options lowercase.

An alternative, more robust fix might have been to change some stuff over here: https://github.com/canismarko/dungeon-sheets/blob/5e07e3861700021be75ad08f036c67a110ed53e7/dungeonsheets/features/features.py#L92

So, the user's selection in feature_choices is lowered, but it is not checked against a lowered t.options in FeatureSelector. Then again, I think it only should check against the keys of t.options in FeatureSelector... Anyway, that's all academic for now, this patch just fixes https://github.com/canismarko/dungeon-sheets/issues/134

Usually, I'd have added https://github.com/canismarko/dungeon-sheets/pull/147/commits/c86857530d24ecc52689bec3c0415525bdbc2238 as well, which is a good way to test this fix, but this time I decided to err on the side of caution :-)