Remove sphinx from requirements.txt too

4 jobs for framediff in 47 minutes and 12 seconds (queued for 23 minutes and 15 seconds)
Status Job ID Name Coverage
  Build
passed #130640
docker
build_linux_27

00:38:28

57.0%
passed #130641
docker
build_linux_36

00:33:44

57.0%
passed #130642
macosx
build_macosx_27

00:29:59

57.0%
passed #130643
macosx
build_macosx_36

00:29:59

57.0%