Fixes caching case-sensitivity

The caching library we're using, fastapi-redis-cache, uses the verbatim (i.e., case-sensitive) arguments to an endpoint to determine if there's a cached response available or not. This occurs before the endpoint's handler is entered, causing every case variant to be a cache miss even if we lowercase the token in the endpoint handler (as I was naively doing before).

To get around this without having to modify the caching library, I've added a decorator lowercase_tok() that runs before the cache decorator, so the decorator ends up seeing the lowercase version of the query token instead and can correctly return a cached version should one exist.

greenelab / word-lapse

Fixes caching case-sensitivity #24