Nothing used to test an i18n/requirements.txt bump - the first real
exercise of a bumped Sphinx/Babel stack was the next scheduled
translations run, well after merging. Template extraction runs the same
toolchain the scheduled workflow uses, in a minute or two, so a broken
bump now fails on its branch instead.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BhJbmhyUpt4qSrKD9cbJ5A