chore(deps): bump config in /bots/echidnabot (#576)

Bumps [config](https://github.com/rust-cli/config-rs) in
`/bots/echidnabot` from 0.15.25 to 0.15.26.

Updates `config` from 0.15.25 to 0.15.26
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/rust-cli/config-rs/blob/main/CHANGELOG.md">config's
changelog</a>.</em></p>
<blockquote>
<h2>[0.15.26] - 2026-09-21</h2>
<h3>Compatibility</h3>
<ul>
<li>Bump MSRV to 1.88</li>
</ul>
<h3>Internal</h3>
<ul>
<li>Upgrade json5 to 1.3</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/rust-cli/config-rs/commit/e368ab295631a6f7125416915d783de9170dbf4d"><code>e368ab2</code></a>
chore: Release config version 0.15.26</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/24c3fc855861dbfc515d4e06f4843d76be0e8526"><code>24c3fc8</code></a>
docs: Update changelog</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/9926dac127ba608a27ae961aebe96a831cb602b9"><code>9926dac</code></a>
chore: Upgrade to json5 (<a
href="https://redirect.github.com/rust-cli/config-rs/issues/774">#774</a>)</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/171077ebe4d1c9b91d87a1f711a7609e35810d0b"><code>171077e</code></a>
chore: Upgrade json5</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/62d3e7a2d2b543a96542ebec1d604dee3e72a836"><code>62d3e7a</code></a>
chore: Update MSRV to 1.88</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/af98be491ea5d96e4def5e9b750d793b36cd8b60"><code>af98be4</code></a>
chore: Update from _rust template (<a
href="https://redirect.github.com/rust-cli/config-rs/issues/772">#772</a>)</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/5516c41f18edb8258c701e402a4966ed16d33fd0"><code>5516c41</code></a>
style: Make clippy happy</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/da28927190b0a84c016914322212db259af694ef"><code>da28927</code></a>
chore: Update from _rust template</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/824cc73f5f5a164b11a73474221765d3b2b472c7"><code>824cc73</code></a>
chore(deps): Update pre-commit hook crate-ci/typos to v1.50.0 (<a
href="https://redirect.github.com/rust-cli/config-rs/issues/100">#100</a>)</li>
<li><a
href="https://github.com/rust-cli/config-rs/commit/970020ad5c7ef8c0fce9cd0c3bc1c1f91d88c7a9"><code>970020a</code></a>
chore(deps): Update pre-commit hook crate-ci/typos to v1.50.0 (<a
href="https://redirect.github.com/rust-cli/config-rs/issues/771">#771</a>)</li>
<li>Additional commits viewable in <a
href="https://github.com/rust-cli/config-rs/compare/v0.15.25...v0.15.26">compare
view</a></li>
</ul>
</details>
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