Workflow fixes
Fixes some workflow issues:
- Installs torch scatter in the CI with the appropriate pre-compiled version
- Removes DeepSpeed and Fairscale from the non-cuda-extension workflows
- Adds the forgotten reports for cuda-extension workflows
- Adds the result of the cuda-extension workflows to be sent to Slack

Also it updates the `deepspeed` dependency in the dependency table, because they seem mismatched on `master` (running `make fixup` fixed it for me)
That's one advantage of using the docker images! We control the exact CUDA and torch versions by controlling the images directly, so it won't break until we manually update it, at which point we should remember to be extra careful about this dependency.