Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Bumps `mermaid-rs-renderer` to
`782b89a7da3f0e91e51f98d00a93acba679be6fb`, which picks up
[1jehuang/mermaid-rs-renderer#95](https://github.com/1jehuang/mermaid-rs-renderer/pull/95),
fixing a panic with partially typed mermaid.

Release Notes:

- Fixed a crash in markdown preview when a mermaid flowchart contained a
partially-typed parallelogram node like `A[/]` or `A[\]`.