Replace the LangChain version of Mustache to chevron

[YusakuNo1]

No description provided.

[Copilot]

PR Overview

This PR replaces the LangChain version of Mustache with the chevron library in the Prompty system to update the template rendering implementation.

• Updated pyproject.toml to add chevron and its type definitions.
• Modified renderers.py to import render from chevron instead of the previous mustache module.

Reviewed Changes

File	Description
runtime/prompty/pyproject.toml	Added chevron and types-chevron dependencies to align with the upgrade.
runtime/prompty/prompty/renderers.py	Replaced the mustache import with chevron's render function for template rendering.

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

[sethjuarez]

Thank you for your contribution! We've migrated Prompty to v2 on main — the codebase has been significantly restructured with AgentSchema-based types, scoped @prompty/* npm packages, and new runtimes.

The v1 code is now preserved on the v1 branch for maintenance. If your change is still relevant for v1, please re-open against the v1 branch. For v2 contributions, please open a new PR against main.

Apologies for any inconvenience, and thanks for your patience!