chore: release v0.12.1 (#90)

## 🤖 New release

* `polyanya`: 0.12.0 -> 0.12.1 (✓ API compatible changes)

<details><summary><i><b>Changelog</b></i></summary><p>



</p></details>

---
This PR was generated with
[release-plz](https://github.com/release-plz/release-plz/).

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polyanya"
-version = "0.12.0"
+version = "0.12.1"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 keywords = ["pathfinding"]