Broken sphinx build

[jeff-cohere]

Cosmic rays have again disintegrated the femto-fibers holding together Sphinx. If we are going to continue to use this collection of Python scripts piled together by people who don't talk to each other often enough, I'm going to have to spend some time teaching this integration to be less aggressive about pulling the latest changes in from Sphinx.

[jedbrown]

Haha, we should pin versions in requirements.txt. Having spent more time using Cargo (Rust), I'm increasingly convinced it was a bad idea for Python to encourage people to leave dependencies unversioned. (Lack of static analysis/care for strict semver also makes this harder in the Python world, but that's another matter.)