chore(deps): bump flask from 3.1.1 to 3.1.3 in /contributing/samples/authn-adk-all-in-one in the pip group across 1 directory

Merge #4571

Bumps the pip group with 1 update in the /contributing/samples/authn-adk-all-in-one directory: [flask](https://github.com/pallets/flask).

Updates `flask` from 3.1.1 to 3.1.3
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/pallets/flask/releases">flask's releases</a>.</em></p>
<blockquote>
<h2>3.1.3</h2>
<p>This is the Flask 3.1.3 security fix release, which fixes a security issue but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release.</p>
<p>PyPI: <a href="https://pypi.org/project/Flask/3.1.3/">https://pypi.org/project/Flask/3.1.3/</a>
Changes: <a href="https://flask.palletsprojects.com/page/changes/#version-3-1-3">https://flask.palletsprojects.com/page/changes/#version-3-1-3</a></p>
<ul>
<li>The session is marked as accessed for operations that only access the keys but not the values, such as <code>in</code> and <code>len</code>. <a href="https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726">GHSA-68rp-wp8r-4726</a></li>
</ul>
<h2>3.1.2</h2>
<p>This is the Flask 3.1.2 fix release, which fixes bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release.</p>
<p>PyPI: <a href="https://pypi.org/project/Flask/3.1.2/">https://pypi.org/project/Flask/3.1.2/</a>
Changes: <a href="https://flask.palletsprojects.com/page/changes/#version-3-1-2">https://flask.palletsprojects.com/page/changes/#version-3-1-2</a>
Milestone: <a href="https://github.com/pallets/flask/milestone/38?closed=1">https://github.com/pallets/flask/milestone/38?closed=1</a></p>
<ul>
<li><code>stream_with_context</code> does not fail inside async views. <a href="https://redirect.github.com/pallets/flask/issues/5774">#5774</a></li>
<li>When using <code>follow_redirects</code> in the test client, the final state of <code>session</code> is correct. <a href="https://redirect.github.com/pallets/flask/issues/5786">#5786</a></li>
<li>Relax type hint for passing bytes IO to <code>send_file</code>. <a href="https://redirect.github.com/pallets/flask/issues/5776">#5776</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/pallets/flask/blob/main/CHANGES.rst">flask's changelog</a>.</em></p>
<blockquote>
<h2>Version 3.1.3</h2>
<p>Released 2026-02-18</p>
<ul>
<li>The session is marked as accessed for operations that only access the keys
but not the values, such as <code>in</code> and <code>len</code>. :ghsa:<code>68rp-wp8r-4726</code></li>
</ul>
<h2>Version 3.1.2</h2>
<p>Released 2025-08-19</p>
<ul>
<li><code>stream_with_context</code> does not fail inside async views. :issue:<code>5774</code></li>
<li>When using <code>follow_redirects</code> in the test client, the final state
of <code>session</code> is correct. :issue:<code>5786</code></li>
<li>Relax type hint for passing bytes IO to <code>send_file</code>. :issue:<code>5776</code></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/pallets/flask/commit/22d924701a6ae2e4cd01e9a15bbaf3946094af65"><code>22d9247</code></a> release version 3.1.3</li>
<li><a href="https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"><code>089cb86</code></a> Merge commit from fork</li>
<li><a href="https://github.com/pallets/flask/commit/c17f379390731543eea33a570a47bd4ef76a54fa"><code>c17f379</code></a> request context tracks session access</li>
<li><a href="https://github.com/pallets/flask/commit/27be9338405382445a7cb01151e084559b98d602"><code>27be933</code></a> start version 3.1.3</li>
<li><a href="https://github.com/pallets/flask/commit/4e652d3f68b90d50aa2301d3b7e68c3fafd9251d"><code>4e652d3</code></a> Abort if the instance folder cannot be created (<a href="https://redirect.github.com/pallets/flask/issues/5903">#5903</a>)</li>
<li><a href="https://github.com/pallets/flask/commit/3d03098a97ddc6a908aa4a50c2ef7381f8297d0a"><code>3d03098</code></a> Abort if the instance folder cannot be created</li>
<li><a href="https://github.com/pallets/flask/commit/407eb76b27884848383a37c7274654f0271e4bc4"><code>407eb76</code></a> document using gevent for async (<a href="https://redirect.github.com/pallets/flask/issues/5900">#5900</a>)</li>
<li><a href="https://github.com/pallets/flask/commit/ac5664d2281533eacafd64f5cc7d5edcdaccab60"><code>ac5664d</code></a> document using gevent for async</li>
<li><a href="https://github.com/pallets/flask/commit/4f79d5b59a56bc4356a97f2e81a35f98cb18d7b3"><code>4f79d5b</code></a> Increase required flit_core version to 3.11 (<a href="https://redirect.github.com/pallets/flask/issues/5865">#5865</a>)</li>
<li><a href="https://github.com/pallets/flask/commit/fe3b215d3ade4db68262dae1a3cdc464a1fc524f"><code>fe3b215</code></a> Increase required flit_core version to 3.11</li>
<li>Additional commits viewable in <a href="https://github.com/pallets/flask/compare/3.1.1...3.1.3">compare view</a></li>
</ul>
</details>
<br />

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COPYBARA_INTEGRATE_REVIEW=#4571 from google:dependabot/pip/contributing/samples/authn-adk-all-in-one/pip-81068183c6 6f577df
PiperOrigin-RevId: 877461954

Author: dependabot[bot]

contributing/samples/authn-adk-all-in-one/requirements.txt

@@ -1,5 +1,5 @@
 google-adk==1.12
-Flask==3.1.1
+Flask==3.1.3
 flask-cors==6.0.1
 python-dotenv==1.1.1
 PyJWT[crypto]==2.10.1