failing test on cran

[sckott]

https://www.r-project.org/nosvn/R.check/r-oldrel-windows-ix86+x86_64/rerddap-00check.html

 -- Error (test-convert_units.R:15:3): convert_units works ----------------------
  Error: Timeout was reached: [upwell.pfeg.noaa.gov] Connection timed out after 10001 milliseconds
  Backtrace:
      x
   1. +-testthat::expect_equal(convert_units(udunits = "degC"), "Cel") test-convert_units.R:15:2
   2. | \-testthat::quasi_label(enquo(object), label, arg = "object")
   3. | \-rlang::eval_bare(expr, quo_get_env(quo))
   4. \-rerddap::convert_units(udunits = "degC")
   5. \-cli$get(query = args)
   6. \-private$make_request(rr)
   7. \-crul:::crul_fetch(opts)
   8. \-curl::curl_fetch_memory(x$url$url, handle = x$url$handle)

on R-oldrel windows