Comment 11 for bug 1875471

I think changing the build-dep to python3-idna << 2.9 is acceptable. It looks like we hit a similar problem with the last SRU and I described the problem and how to fix the specific issue at the time at https://bugs.launchpad.net/ubuntu/+source/python-acme/+bug/1836823/comments/23.

In this case, allowing python3-idna 2.8 should be fine because Focal has python3-requests 2.22.0 and the constraints that version of requests puts on idna are "idna>=2.5,<2.9" which can be seen at https://github.com/psf/requests/blob/v2.22.0/setup.py#L46.