Bump pypdf from 6.8.0 to 6.9.1 in /libs/langchain-mongodb in the uv group across 1 directory (#353)

Bumps the uv group with 1 update in the /libs/langchain-mongodb
directory: [pypdf](https://github.com/py-pdf/pypdf).

Updates `pypdf` from 6.8.0 to 6.9.1
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/py-pdf/pypdf/releases">pypdf's
releases</a>.</em></p>
<blockquote>
<h2>Version 6.9.1, 2026-03-17</h2>
<h2>What's new</h2>
<h3>Security (SEC)</h3>
<ul>
<li>Improve performance and limit length of array-based content streams
(<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3686">#3686</a>)
by <a
href="https://github.com/stefan6419846"><code>@​stefan6419846</code></a></li>
</ul>
<p><a href="https://github.com/py-pdf/pypdf/compare/6.9.0...6.9.1">Full
Changelog</a></p>
<h2>Version 6.9.0, 2026-03-15</h2>
<h2>What's new</h2>
<h3>New Features (ENH)</h3>
<ul>
<li>Expose /Perms verification result on Encryption object (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3672">#3672</a>)
by <a
href="https://github.com/costajohnt"><code>@​costajohnt</code></a></li>
</ul>
<h3>Performance Improvements (PI)</h3>
<ul>
<li>Fix O(n²) performance in NameObject read/write (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3679">#3679</a>)
by <a
href="https://github.com/dmitry-kostin"><code>@​dmitry-kostin</code></a></li>
<li>Batch-parse all objects in ObjStm on first access (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3677">#3677</a>)
by <a
href="https://github.com/dmitry-kostin"><code>@​dmitry-kostin</code></a></li>
</ul>
<h3>Bug Fixes (BUG)</h3>
<ul>
<li>Avoid sharing array-based content streams between pages (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3681">#3681</a>)
by <a
href="https://github.com/stefan6419846"><code>@​stefan6419846</code></a></li>
<li>Avoid accessing invalid page when inserting blank page under some
conditions (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3529">#3529</a>)
by <a href="https://github.com/j-t-1"><code>@​j-t-1</code></a></li>
</ul>
<p><a href="https://github.com/py-pdf/pypdf/compare/6.8.0...6.9.0">Full
Changelog</a></p>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/py-pdf/pypdf/blob/main/CHANGELOG.md">pypdf's
changelog</a>.</em></p>
<blockquote>
<h2>Version 6.9.1, 2026-03-17</h2>
<h3>Security (SEC)</h3>
<ul>
<li>Improve performance and limit length of array-based content streams
(<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3686">#3686</a>)</li>
</ul>
<p><a href="https://github.com/py-pdf/pypdf/compare/6.9.0...6.9.1">Full
Changelog</a></p>
<h2>Version 6.9.0, 2026-03-15</h2>
<h3>New Features (ENH)</h3>
<ul>
<li>Expose /Perms verification result on Encryption object (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3672">#3672</a>)</li>
</ul>
<h3>Performance Improvements (PI)</h3>
<ul>
<li>Fix O(n²) performance in NameObject read/write (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3679">#3679</a>)</li>
<li>Batch-parse all objects in ObjStm on first access (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3677">#3677</a>)</li>
</ul>
<h3>Bug Fixes (BUG)</h3>
<ul>
<li>Avoid sharing array-based content streams between pages (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3681">#3681</a>)</li>
<li>Avoid accessing invalid page when inserting blank page under some
conditions (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3529">#3529</a>)</li>
</ul>
<p><a href="https://github.com/py-pdf/pypdf/compare/6.8.0...6.9.0">Full
Changelog</a></p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/py-pdf/pypdf/commit/0e5157c2d9440c3594de43ffe27745eb474a2fb9"><code>0e5157c</code></a>
REL: 6.9.1</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/0b5d05de59a055c132b435ee2375bc32ff04d48e"><code>0b5d05d</code></a>
SEC: Improve performance and limit length of array-based content streams
(<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3686">#3686</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/87aa1d436b91c055f6ed1a4ed4146567e5db67b3"><code>87aa1d4</code></a>
DEV: Remove unused reverse encoding dicts (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3685">#3685</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/84f526622657d3da2068d5c05c0cba8746aec7b0"><code>84f5266</code></a>
MAINT: Use placeholder-based approach for logger_error (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3673">#3673</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/8f1f4aa8607a1e3b4730d67ca24e6b8f86bf526f"><code>8f1f4aa</code></a>
REL: 6.9.0</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/5a9a0da71714c4361b38ebdcaf304291569d7a2f"><code>5a9a0da</code></a>
BUG: Avoid sharing array-based content streams between pages (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3681">#3681</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/a3451e8f30454cc5500e03d81f6827351499af8a"><code>a3451e8</code></a>
ENH: Expose /Perms verification result on Encryption object (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3672">#3672</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/3a4e913c4cbee207d72fd63d835740ad9825d1bf"><code>3a4e913</code></a>
PI: Fix O(n²) performance in NameObject read/write (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3679">#3679</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/cf2e5187b0fccd8a26f7b8fb1a140f42847b53d4"><code>cf2e518</code></a>
PI: Batch-parse all objects in ObjStm on first access (<a
href="https://redirect.github.com/py-pdf/pypdf/issues/3677">#3677</a>)</li>
<li><a
href="https://github.com/py-pdf/pypdf/commit/2cfcd7ea9d175f1bbd243043a432a6b9470baa37"><code>2cfcd7e</code></a>
BUG: Avoid accessing invalid page when inserting blank page under some
condit...</li>
<li>See full diff in <a
href="https://github.com/py-pdf/pypdf/compare/6.8.0...6.9.1">compare
view</a></li>
</ul>
</details>
<br />


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