Use requests for downloading schedules
Use requests for downloading schedules

urlretrieve seems to have a problem with relative `Location` headers,
which is affecting the IADB import. But anyway, requests is generally a
bit nicer, so let’s use that.

pwyf/IATI-Implementation-Schedules,pwyf/IATI-Implementation-Schedules,pwyf/IATI-Implementation-Schedules,pwyf/IATI-Implementation-Schedules