Update Rust crate tiktoken-rs to 0.6.0 (#21900)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [tiktoken-rs](https://redirect.github.com/zurawiki/tiktoken-rs) |
workspace.dependencies | minor | `0.5.9` -> `0.6.0` |

---

### Release Notes

<details>
<summary>zurawiki/tiktoken-rs (tiktoken-rs)</summary>

###
[`v0.6.0`](https://redirect.github.com/zurawiki/tiktoken-rs/releases/tag/v0.6.0)

[Compare
Source](https://redirect.github.com/zurawiki/tiktoken-rs/compare/v0.5.9...v0.6.0)

**Minor version release signifies a breaking change in 0.x**

#### What's Changed

- Add support for chatgpt-4o-latest by
[@&#8203;Congyuwang](https://redirect.github.com/Congyuwang) in
[https://github.com/zurawiki/tiktoken-rs/pull/85](https://redirect.github.com/zurawiki/tiktoken-rs/pull/85)
- Refactor internals to make future updates to tiktoken easier to merge
-   Do not expose tiktoken internal modules and functions
-   Update dependencies

#### New Contributors

- [@&#8203;Congyuwang](https://redirect.github.com/Congyuwang) made
their first contribution in
[https://github.com/zurawiki/tiktoken-rs/pull/85](https://redirect.github.com/zurawiki/tiktoken-rs/pull/85)

**Full Changelog**:
https://github.com/zurawiki/tiktoken-rs/compare/v0.5.9...v0.6.0

</details>

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---

Release Notes:

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Cargo.toml

@@ -472,7 +472,7 @@ sys-locale = "0.3.1"
 sysinfo = "0.31.0"
 tempfile = "3.9.0"
 thiserror = "1.0.29"
-tiktoken-rs = "0.5.9"
+tiktoken-rs = "0.6.0"
 time = { version = "0.3", features = [
     "macros",
     "parsing",