Switch food bank/free food datasource to GPCFB

[maxachis]

Need to talk to Kelsey Gross about how to access the Greater Pittsburgh Community Food Bank datasource on this

We'd probably want to filter out the food bank sites on the other sources, since we don't get information from just one source on the Food Bank -- they might come on either the SNAP or WIC ones -- so we make sure the one from the food bank is the real list.