textproc/py-normality: Update to 3.1.0

• Fold ICU option because its requirement, py-pyicu, is now a mandatory dependency since the 3.0.0 release.

• Switch to GitHub for a while because no sdist tarballs are available at PyPI.

Changelog since 2.5.0:

https://github.com/pudo/normality/compare/2.5.0...3.1.0