deepseek-chat and deepseek-reasoner upgraded to DeepSeek-V3.1 with hybrid reasoning

Both deepseek-chat and deepseek-reasoner have been upgraded to DeepSeek-V3.1. deepseek-chat corresponds to DeepSeek-V3.1's non-thinking mode, while deepseek-reasoner corresponds to its thinking mode.

• Key updates in DeepSeek-V3.1:
  • Hybrid reasoning architecture: A single model supports both thinking mode and non-thinking mode
  • Improved reasoning efficiency: Compared to DeepSeek-R1-0528, DeepSeek-V3.1-Think provides answers in significantly less time
  • Enhanced agent capabilities: With post-training optimization, the new model achieves major improvements in tool usage and intelligent agent tasks
    • SWE-bench Verified: 66.0
    • SWE-bench Multilingual: 54.5
    • Terminal-bench: 31.3