Update Tokenizer to 0.21 and mistral.rs

[Jeadie]

🗣 Description

• Update mistral.rs, which requires moving all dependencies onto tokenizers = 0.21.0.
• PRs
  • Add changes from EricLBuehler/mistral.rs mistral.rs#10
  • Update tokenizer to 0.21 text-splitter#2
  • update tokenizer to 0.21 text-embeddings-inference#11
  • Fix mistral run with metal feature and current-thread runtimes support mistral.rs#11

🔨 Related Issues

• This drags in a fix in mistral.rs that fixes Phi-based models: phi3 output garbage on master EricLBuehler/mistral.rs#956