document breaking change `pool` no longer accepted

[JosiahParry]

Hey team!

Would it be possible to add a line to NEWS.md that indicates that a breaking change was made in httr2 where pool = was deprecated in favor of the new max_active argument.

We've bumped the minimum required version of httr2 at: https://github.com/R-ArcGIS/arcgisgeocode/pull/40/files

I struggled to track down the change again and it would be great if it was listed in NEWS.md specifically as a "Breaking" change

req_perform_parallel(pool) now is deprecated in favour of a new max_active argument (#681).

[hadley]

I don't think this is a breaking change in the sense that existing code will continue to work? (Albeit with a deprecation warning).

[JosiahParry]

Sorry! My apologies. I think the error I ran into was backwards—updating to use max_active but somehow < 1.1.1 was installed.