Bump clap from 4.5.2 to 4.5.3 in /cmd/pinniped-proxy (#7597)

Bumps [clap](https://github.com/clap-rs/clap) from 4.5.2 to 4.5.3.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/clap-rs/clap/releases">clap's
releases</a>.</em></p>
<blockquote>
<h2>v4.5.3</h2>
<h2>[4.5.3] - 2024-03-15</h2>
<h3>Internal</h3>
<ul>
<li><em>(derive)</em> Update <code>heck</code></li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/clap-rs/clap/blob/master/CHANGELOG.md">clap's
changelog</a>.</em></p>
<blockquote>
<h2>[4.5.3] - 2024-03-15</h2>
<h3>Internal</h3>
<ul>
<li><em>(derive)</em> Update <code>heck</code></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/clap-rs/clap/commit/4e07b438584bb8a19e37599d4c5b11797bec5579"><code>4e07b43</code></a>
chore: Release</li>
<li><a
href="https://github.com/clap-rs/clap/commit/8247c7ddf05d8023729ac180d8e8df260f1da5ff"><code>8247c7d</code></a>
docs: Update changelog</li>
<li><a
href="https://github.com/clap-rs/clap/commit/677c52ce0870115845a4c42e204f6c049b81a1e7"><code>677c52c</code></a>
chore: Update <code>heck</code> requirement (<a
href="https://redirect.github.com/clap-rs/clap/issues/5396">#5396</a>)</li>
<li>See full diff in <a
href="https://github.com/clap-rs/clap/compare/v4.5.2...v4.5.3">compare
view</a></li>
</ul>
</details>
<br />


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