Consider ulklc/covid19-timeseries as optional source

[imjoshellis]

Because my app relies on recovered data to estimate "active" cases, I'm going to have to switch from this API (which is lovely, btw) to this data, unless you want to add it as an optional source here?

https://github.com/ulklc/covid19-timeseries

[ExpDev07]

I’ll look into adding it!