We should scrape [the categories and topics]. We have no idea what the maintenance of this repo will look like over time. It's certainly had its lulls over time, so let's make it withstand the lack of us

Originally posted by @RitwikGupta in #203 (comment)

In #203, I rewrote news.py to scrape Pitt news articles from the Pittwire website, but I hard-coded the list of news categories and topics. We should scrape these values instead so that we don't have to keep them updated ourselves. Ideally, news.py should only scrape these values once, when the users uses a function from the module for the first time, so that the values are available for all subsequent function calls.