chore(deps-rs): bump serde from 1.0.203 to 1.0.204 (#455)

Bumps [serde](https://github.com/serde-rs/serde) from 1.0.203 to
1.0.204.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/serde-rs/serde/releases">serde's
releases</a>.</em></p>
<blockquote>
<h2>v1.0.204</h2>
<ul>
<li>Apply #[diagnostic::on_unimplemented] attribute on Rust 1.78+ to
suggest adding serde derive or enabling a &quot;serde&quot; feature flag
in dependencies (<a
href="https://redirect.github.com/serde-rs/serde/issues/2767">#2767</a>,
thanks <a
href="https://github.com/weiznich"><code>@​weiznich</code></a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/serde-rs/serde/commit/18dcae0a77632fb4767a420c550cb41991f750b8"><code>18dcae0</code></a>
Release 1.0.204</li>
<li><a
href="https://github.com/serde-rs/serde/commit/58c307f9cc28a19d73a0e2869f6addf9a8a329f9"><code>58c307f</code></a>
Alphabetize list of rustc-check-cfg</li>
<li><a
href="https://github.com/serde-rs/serde/commit/8cc4809414a83de0d41eac38ecfa1040e088b61e"><code>8cc4809</code></a>
Merge pull request <a
href="https://redirect.github.com/serde-rs/serde/issues/2769">#2769</a>
from dtolnay/onunimpl</li>
<li><a
href="https://github.com/serde-rs/serde/commit/1179158defc5351467cbd2c340b7e1498391bce4"><code>1179158</code></a>
Update ui test with diagnostic::on_unimplemented from PR 2767</li>
<li><a
href="https://github.com/serde-rs/serde/commit/91aa40e749620f31bf7db01c772e672f023136b5"><code>91aa40e</code></a>
Add ui test of unsatisfied serde trait bound</li>
<li><a
href="https://github.com/serde-rs/serde/commit/595019e979ebed5452b550bf901abcab2cf4e945"><code>595019e</code></a>
Cut test_suite from workspace members in old toolchain CI jobs</li>
<li><a
href="https://github.com/serde-rs/serde/commit/b0d7917f88978eda264f8fbac13b46ece35f5348"><code>b0d7917</code></a>
Pull in trybuild 'following types implement trait' fix</li>
<li><a
href="https://github.com/serde-rs/serde/commit/8e6637a1e44c30dffd37322a7107d434cd751722"><code>8e6637a</code></a>
Merge pull request <a
href="https://redirect.github.com/serde-rs/serde/issues/2767">#2767</a>
from weiznich/feature/diagnostic_on_unimplemented</li>
<li><a
href="https://github.com/serde-rs/serde/commit/694fe0595358aa0857120a99041d99975b1a8a70"><code>694fe05</code></a>
Use the <code>#[diagnostic::on_unimplemented]</code> attribute when
possible</li>
<li><a
href="https://github.com/serde-rs/serde/commit/f3dfd2a2375d9caf15a18ec657dde51a32caf6ed"><code>f3dfd2a</code></a>
Suppress dead code warning in test of unit struct remote derive</li>
<li>Additional commits viewable in <a
href="https://github.com/serde-rs/serde/compare/v1.0.203...v1.0.204">compare
view</a></li>
</ul>
</details>
<br />


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