graphics/py-sorl-thumbnail: Update to 12.11.0

• Switch to the PEP517 build framework and adjust the related bits of the DOCS option accordingly.

• Change to the more preferred DISTVERSION as well.

Changelog:

https://github.com/jazzband/sorl-thumbnail/releases/tag/12.11.0

PR: 289339
Approved by: Kevin Golding (maintainer)