fix always repeating downloads 3 times (#3978)

(cherry picked from commit 667d8ae)

src/PlatformEngines.jl

@@ -357,6 +357,7 @@ function download_verify(
  for i in 1:attempts
  try
  download(url, dest; verbose=verbose || !quiet_download)
+ break
  catch err
  @debug "download and verify failed on attempt $i/$attempts" url dest err
  # for system errors like `no space left on device` exit after first try