devel/py-requests: Bump pinned idna dependency version

py-idna was updated to 2.7 in ports r476560. py-requests had its idna dependency
pinned to <2.7.

That broke all py-requests dependents.

This change backports part of an upstream commit [1] that bumped the dependency.

Whisper of a dream: It would be really cool if *_DEPENDS could declare multiple
versions in its scheme. We'd pick up these issues much earlier, and be able to
declare dependencies more accurately.</pony>

[1] https://github.com/requests/requests/commit/991e8b76b7a9d21f698b24fa0058d3d5968721bc

PR: 230430
Reported by: <Trond Endrestol ximalas info>