SPPO Implementation on Axolotl!

[kaykyr]

Hey guys! For who is interested, I recently submitted a pull request to implements SPPO on Axolotl trainer, you can fallow the pull request here:
axolotl-ai-cloud/axolotl#1735

Original SPPO implementation fork:
https://github.com/kaykyr/axolotl

See examples/llama3/sppo-qlora-8b.yml config file to see how train SPPO.