MINOR: [C#] Bump pythonnet from 3.0.2 to 3.0.3 in /csharp (apache#38291)

Bumps [pythonnet](https://github.com/pythonnet/pythonnet) from 3.0.2 to 3.0.3.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/pythonnet/pythonnet/releases">pythonnet's releases</a>.</em></p>
<blockquote>
<h2>v3.0.3</h2>
<h2>What's Changed</h2>
<ul>
<li>change PyScope to PyModule by <a href="https://github.com/OmkarBorhade98"><code>@​OmkarBorhade98</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2231">pythonnet/pythonnet#2231</a></li>
<li>use enum name in repr by <a href="https://github.com/koubaa"><code>@​koubaa</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2239">pythonnet/pythonnet#2239</a></li>
<li>ARM CI fix by <a href="https://github.com/lostmsu"><code>@​lostmsu</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2256">pythonnet/pythonnet#2256</a></li>
<li>Python 3.12 by <a href="https://github.com/filmor"><code>@​filmor</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2249">pythonnet/pythonnet#2249</a></li>
<li>Only run docs CI/main CI for corresponding changes by <a href="https://github.com/lostmsu"><code>@​lostmsu</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2257">pythonnet/pythonnet#2257</a></li>
<li>Revert &quot;Only run docs CI/main CI for corresponding changes&quot; by <a href="https://github.com/filmor"><code>@​filmor</code></a> in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2260">pythonnet/pythonnet#2260</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/OmkarBorhade98"><code>@​OmkarBorhade98</code></a> made their first contribution in <a href="https://redirect.github.com/pythonnet/pythonnet/pull/2231">pythonnet/pythonnet#2231</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a href="https://github.com/pythonnet/pythonnet/compare/v3.0.2...v3.0.3">https://github.com/pythonnet/pythonnet/compare/v3.0.2...v3.0.3</a></p>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/pythonnet/pythonnet/blob/master/CHANGELOG.md">pythonnet's changelog</a>.</em></p>
<blockquote>
<h2><a href="https://github.com/pythonnet/pythonnet/releases/tag/v3.0.3">3.0.3</a> - 2023-10-11</h2>
<h3>Added</h3>
<ul>
<li>Support for Python 3.12</li>
</ul>
<h3>Changed</h3>
<ul>
<li>Use enum name in <code>repr</code></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/pythonnet/pythonnet/commit/0a5a63ccc4ee1e104ab0aae75ede8aa3441a3481"><code>0a5a63c</code></a> Release 3.0.3</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/5a4a986f9e2b9f4f505db68809f45a63c39b1418"><code>5a4a986</code></a> Revert &quot;only run docs CI/main CI for corresponding changes (<a href="https://redirect.github.com/pythonnet/pythonnet/issues/2257">#2257</a>)&quot; (<a href="https://redirect.github.com/pythonnet/pythonnet/issues/2260">#2260</a>)</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/04670ea1c8a761944e19ac89acd18a43a82cc352"><code>04670ea</code></a> only run docs CI/main CI for corresponding changes (<a href="https://redirect.github.com/pythonnet/pythonnet/issues/2257">#2257</a>)</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/88418da6a87f3dcdd861ff0022d8beb6164ae3ee"><code>88418da</code></a> Merge pull request <a href="https://redirect.github.com/pythonnet/pythonnet/issues/2249">#2249</a> from pythonnet/python-3.12</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/293f8b1d810db1e63253b950a4b4844b35c38bab"><code>293f8b1</code></a> Python 3.12 has been released, use final version</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/fb494705652af998a4f346aeb88ebff836c72eb4"><code>fb49470</code></a> Ignore test-case on Python 3.12</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/080d1bd59f2b231db2081474cf126e46aa039505"><code>080d1bd</code></a> For now skip over &quot;new style&quot; weakrefs in clear</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/8dfe4080d642397a7efcb52b8d3aa69da1675713"><code>8dfe408</code></a> Remove deprecated function call</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/d057724e5167d7088a3dc77310a37c38473e318d"><code>d057724</code></a> Update changelog</li>
<li><a href="https://github.com/pythonnet/pythonnet/commit/7a31d38755c71d0385bf28e758ab9cf96a2db481"><code>7a31d38</code></a> Add 3.12 to CI and metadata</li>
<li>Additional commits viewable in <a href="https://github.com/pythonnet/pythonnet/compare/v3.0.2...v3.0.3">compare view</a></li>
</ul>
</details>
<br />

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csharp/test/Apache.Arrow.Tests/Apache.Arrow.Tests.csproj

@@ -17,7 +17,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
     <PackageReference Include="xunit.skippablefact" Version="1.4.13" />
-    <PackageReference Include="pythonnet" Version="3.0.2" />
+    <PackageReference Include="pythonnet" Version="3.0.3" />
   </ItemGroup>
 
   <ItemGroup>