chore(deps-py): bump graphviz from 0.20.1 to 0.20.3 (#326)

Bumps [graphviz](https://github.com/xflr6/graphviz) from 0.20.1 to
0.20.3.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/xflr6/graphviz/blob/master/CHANGES.rst">graphviz's
changelog</a>.</em></p>
<blockquote>
<h2>Version 0.20.3</h2>
<p>Revert improvements to the internal
<code>tools.deprecate_positional_args()</code>
decorator that caused false positive
<code>PendingDeprecationWarning: The signature of ... will be
reduced</code>
warnings that have been misinterpreted in the <code>0.20.2</code>
release process.</p>
<h2>Version 0.20.2</h2>
<p>Drop Python 3.7 support (end of life 27 Jun 2023).</p>
<p>Tag Python 3.11 and 3.12 support.</p>
<p>Add caveat about <code>labe</code> escaping/quoting to
<code>.node()</code> and <code>.render()</code>
API docs.</p>
<p>Document that <code>doctest_skip_exe()</code> lines in doctest should
be ignored.</p>
<p>Improve internal <code>tools.deprecate_positional_args()</code>
decorator
and fix incorect test assertion.</p>
<p>Update GitHub actions.</p>
<p>Pin <code>pytest</code> test dependency to <code>&lt;8.1</code> as a
workaround
for <code>import file mismatch error</code> related to
<code>conftest.py</code> files,
in <code>pytest</code> <code>8.1.1</code>, see <a
href="https://redirect.github.com/pytest-dev/pytest/issues/12123">pytest-dev/pytest#12123</a>.</p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/xflr6/graphviz/commit/cbfbeadc438e654ee3534d08d531c0d5dc2a7704"><code>cbfbead</code></a>
release 0.20.3</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/dbdef1f105b1924a85c01e37dc851147bab7f2f6"><code>dbdef1f</code></a>
Better document pytest version pinning</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/8d8c65913706751a246f7b00cbc513c69cc217ba"><code>8d8c659</code></a>
Revert &quot;ignore own signature-related deprecation warnings in
release process&quot;</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/195855c77fa3540baa5ffc030d741eb9fbbb122d"><code>195855c</code></a>
Revert &quot;fix number of positional arguments in deprecation warning
messages&quot;</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/78daf45dfa779370c542375995d4e59d86d2c1bd"><code>78daf45</code></a>
bump version for development</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/34fb16bcb6c47731888e0a28e5ead579484c668f"><code>34fb16b</code></a>
release 0.20.2</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/7fab480418ebdf5f4b19b24c985b853542c97439"><code>7fab480</code></a>
ignore own signature-related deprecation warnings in release
process</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/09e216108c16a1aa913ce7bf3b57450e97f63d07"><code>09e2161</code></a>
run update-help.py with Python 3.12</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/24507fce3761fb245f063a7a24f0902f03f33836"><code>24507fc</code></a>
document excluded pytest 8.1.1 version</li>
<li><a
href="https://github.com/xflr6/graphviz/commit/7fb9191378a33c5e1884d635122c097c1c3ef02b"><code>7fb9191</code></a>
fix inline literal start-string without end-string</li>
<li>Additional commits viewable in <a
href="https://github.com/xflr6/graphviz/compare/0.20.1...0.20.3">compare
view</a></li>
</ul>
</details>
<br />


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