Adds option for http agent for user in slack callback (#9836)
* Adds option for http agent for user in slack callback
* Adds changelog fragment for 9836 issue
* Apply suggestions from code review
Co-authored-by: Felix Fontein <felix@fontein.de>
* Fix typo.
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Co-authored-by: Abhijeet Kasurde <akasurde@redhat.com>
Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit 941df094ca)
Co-authored-by: Anwesha Das <anwesha@das.community>
