Bump tox from 4.19.0 to 4.20.0 (#416)

Bumps [tox](https://github.com/tox-dev/tox) from 4.19.0 to 4.20.0.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/tox-dev/tox/blob/main/docs/changelog.rst">tox's
changelog</a>.</em></p>
<blockquote>
<h2>v4.20.0 (2024-09-18)</h2>
<p>Features - 4.20.0</p>
<pre><code>- Separate the list dependencies functionality to a separate
abstract class allowing code reuse in plugins (such as
  ``tox-uv``) - by :gaborbernat`. (:issue:`3347`)
</code></pre>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/tox-dev/tox/commit/a04cc3afa08e4641ba8419eb320e738d4ef8180c"><code>a04cc3a</code></a>
release 4.20.0</li>
<li><a
href="https://github.com/tox-dev/tox/commit/4d8f5fd826276b59a73a4851dcc2fbb388a0d574"><code>4d8f5fd</code></a>
Separate list dependencies to a separate installer class (<a
href="https://redirect.github.com/tox-dev/tox/issues/3347">#3347</a>)</li>
<li><a
href="https://github.com/tox-dev/tox/commit/0cb816c572a1b549c9e1b20d3bee4ed3fbde6b43"><code>0cb816c</code></a>
YML to YAML</li>
<li>See full diff in <a
href="https://github.com/tox-dev/tox/compare/4.19.0...4.20.0">compare
view</a></li>
</ul>
</details>
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