fix(deps): update dependency llama-index to v0.12.8

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
llama-index (source)	0.12.5 -> 0.12.8

---

Release Notes

run-llama/llama_index (llama-index)

v0.12.8

Compare Source

• Fix exclude text in document serialization (#​17341)
• Fix missing aput in awrite_response_to_history (#​17338)

v0.12.7

Compare Source

• fix: add a timeout to langchain callback handler (#​17296)
• fix: make Document serialization event more backward compatible (#​17312)

v0.12.6

Compare Source

• [bug fix] Ensure that StopEvent gets cleared from Context._in_progress["_done"] after a Workflow run (#​17300)
• fix: add a timeout to langchain callback handler (#​17296)
• tweak User vs tool in react prompts (#​17273)
• refact: Refactor Document to be natively multimodal (#​17204)
• fix: make ImageDocument derive from Document, backward compatible (#​17259)
• fix: accept already base64-encoded data in ImageBlock (#​17244)
• fix(metrics): fixed NDCG calculation and updated previous tests (#​17236)
• fix: remove llama-index-legacy dependency in llama-index-core (#​17231)
• Refined the default documentation generation for function tools (#​17208)

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.