Patch release v5.12.1

Updated the lower bound for PEFT and a fix for auto tokenizer to properly resolve the mistral tokenizer (when mistral-common is installed). This is similar to v.5.10.3 minus the fixes that were already included in the main release - vLLM will first target 5.10.3 🤗

• Fix peft lower bound #46605 by @hmellor (#46605)
• mistral common backend fix #46667 by @itazap (#46667)

Full Changelog: v5.12.0...v5.12.1