The output can be configured via the 'output.progress'
config value.
Possible values:
- true: Show the default progress indicator
"[{current}/{total}] {url}" (default)
- false: Never show the progress indicator
- <string>: Show the progress indicator using this
as a custom format string(1).
Possible replacement keys are:
- current: current URL index
- total : total number of URLs
- url : current URL
(1) https://docs.python.org/3/library/string.html#formatstrings
