Update Rust crate inventory to v0.3.20 (#26180)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [inventory](https://redirect.github.com/dtolnay/inventory) |
workspace.dependencies | patch | `0.3.19` -> `0.3.20` |

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### Release Notes

<details>
<summary>dtolnay/inventory (inventory)</summary>

###
[`v0.3.20`](https://redirect.github.com/dtolnay/inventory/releases/tag/0.3.20)

[Compare
Source](https://redirect.github.com/dtolnay/inventory/compare/0.3.19...0.3.20)

-   Documentation improvements

</details>

---

### Configuration

📅 **Schedule**: Branch creation - "after 3pm on Wednesday" in timezone
America/New_York, 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.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

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Release Notes:

- N/A

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