Retry Socrata API requests in case of failure in vignettes

[jeancochrane]

Damon noticed that the tax rate vignette sometimes fails to render because the Socrata API closes the connection during a query. See these logs for an example:

! Failed to render 'vignettes/tax_rates.Rmd'.
✖ Quitting from tax_rates.Rmd:65-94 [unnamed-chunk-3]
✖ Warning message:
✖ call dbDisconnect() when finished working with a connection
Caused by error:
! Failure when receiving data from the peer [datacatalog.cookcountyil.gov]:
Recv failure: Connection reset by peer
Backtrace:
    ▆
 1. ├─httr::GET(...)
 2. │ └─httr:::request_perform(req, hu$handle$handle)
 3. │   ├─httr:::request_fetch(req$output, req$url, handle)
 4. │   └─httr:::request_fetch.write_memory(req$output, req$url, handle)
 5. │     └─curl::curl_fetch_memory(url, handle = handle)
 6. └─curl:::raise_libcurl_error(...)
Execution halted

Our Socrata API work in data-architecture has revealed that closed connections are common when working with the Socrata API, so this PR tweaks our vignettes to use the RETRY() httr function to retry requests to Socrata in case of closed connections.

There's no definitive way to test that this change resolves the sporadic errors, since they are non-deterministic and so not reproducible. But I don't think this change will hurt, and we can re-evaluate it later if we notice builds continuing to fail.

[Damonamajor]

This makes perfect sense to me!

[kyrasturgill]

Thanks for catching and addressing this!