misc/py-litellm: update to 1.31.8

Changelog:

• https://github.com/BerriAI/litellm/releases/tag/v1.29.7
• https://github.com/BerriAI/litellm/releases/tag/v1.30.0
• https://github.com/BerriAI/litellm/releases/tag/v1.30.1
• https://github.com/BerriAI/litellm/releases/tag/v1.30.2
• https://github.com/BerriAI/litellm/releases/tag/v1.30.3
• https://github.com/BerriAI/litellm/releases/tag/v1.30.4
• https://github.com/BerriAI/litellm/releases/tag/v1.30.5
• https://github.com/BerriAI/litellm/releases/tag/v1.30.6
• https://github.com/BerriAI/litellm/releases/tag/v1.30.7
• https://github.com/BerriAI/litellm/releases/tag/v1.31.2
• https://github.com/BerriAI/litellm/releases/tag/v1.31.3
• https://github.com/BerriAI/litellm/releases/tag/v1.31.4
• https://github.com/BerriAI/litellm/releases/tag/v1.31.5
• https://github.com/BerriAI/litellm/releases/tag/v1.31.6
• https://github.com/BerriAI/litellm/releases/tag/v1.31.7
• https://github.com/BerriAI/litellm/releases/tag/v1.31.8

Reported by: Repology