Update LangGraph Python dependency to v1.2+ from ">= 0.2.60, <= 0.4.8"

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Contribution guide.

🔴 Required Information

Is your feature request related to a specific problem?

LangGraph is pinned to an old version: https://github.com/google/adk-python/blob/main/pyproject.toml#L159.

Describe the Solution You'd Like

Update LangGraph to v1.2+ (Python).

Impact on your work

We're unable to adopt ADK without support for LangGraph v1+ (Python).

Willingness to contribute

Are you interested in implementing this feature yourself or submitting a PR?
No

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🟡 Recommended Information

Describe Alternatives You've Considered

Proposed API / Implementation

Additional Context

[sanketpatil06]

Hi @declanryan-cmg, Thanks for raising this. the request is currently being reviewed, and we will let you know if anything further is needed. Thank you for your understanding.

[wuliang229]

Should already be fixed in the toml file to support langgraph v1+