The boto3 package is used for AWS API. It is used in the https://gitlab.isc.org/isc-projects/bind9-shotgun-ci repository. Pre-installing this package speeds up the tests in that repo.
usage: https://gitlab.isc.org/isc-projects/bind9-shotgun-ci/-/pipelines/108173
I've also tried to rebuild the image to check if any update breaks something in bind9 CI. I'm not sure if now is a good time to be updating this image, but as of 2022-06-24, it seems like the update is okay. I only stumbled upon new TSAN failures on v9_18 which may or may not be related to the clang update from 14.0.5 to 14.0.6. There's also an unrelated failure on debian strech due to old Python.