Switch back to shortened URL in Ch 2

[juliasilge]

In #302 we found we had to switch out the shortened URL http://bit.ly/raw-train-data-csv that we use in Chapter 2 for the long, original URL https://data.cityofchicago.org/api/views/5neh-572f/rows.csv?accessType=DOWNLOAD&bom=true&format=true.

Both Max and I can access the shortened URL from R just fine but it failed on GH actions multiple times. Let's see if we can switch back at some point.