Bump serde_yaml from 0.9.19 to 0.9.21 (#2789)

Bumps [serde_yaml](https://github.com/dtolnay/serde-yaml) from 0.9.19 to 0.9.21.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/dtolnay/serde-yaml/releases">serde_yaml's releases</a>.</em></p>
<blockquote>
<h2>0.9.21</h2>
<ul>
<li>Make <code>Tag::new</code> panic if given empty string, since YAML has no syntax for an empty tag</li>
</ul>
<h2>0.9.20</h2>
<ul>
<li>Allow an empty YAML document to deserialize to <code>None</code> or <code>Value::Null</code>, in addition to the previously supported empty vector, empty map, and struct with no required fields</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/8057faddd6bbe647d0bdae19d98087c7edced5d3"><code>8057fad</code></a> Release 0.9.21</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/19a7bd3d9bbba98373e6577805aad55a189680f6"><code>19a7bd3</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/371">#371</a> from dtolnay/emptytag</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/ebb4b7af3a78f1e80078fbd1589c825edb41e0ab"><code>ebb4b7a</code></a> Fix deserialization of tag !&lt;%21&gt;</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/879a57fe919aca83f7334b7ab012d403481db728"><code>879a57f</code></a> Factor out conversion function from libyaml Tag to tag string</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/e3b9a02a137dd3ba9a337f636469f28ae8f7bc71"><code>e3b9a02</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/370">#370</a> from dtolnay/emptytag</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/ef435495d1f4641ab2d3d119c4189ac6d59d9379"><code>ef43549</code></a> Treat Tag::new(&quot;!&quot;) as tag %21, instead of empty tag</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/221154cc1b003c4da3c54b065de41787749caa63"><code>221154c</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/369">#369</a> from dtolnay/emptytag</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/39a866c695e23cb2607020b9a0d92f4544d92987"><code>39a866c</code></a> Reuse Tag visitor in Value's Deserialize impl</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/80e53a5166f3a560b7753133d9fa8bebe352f464"><code>80e53a5</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/368">#368</a> from dtolnay/emptytag</li>
<li><a href="https://github.com/dtolnay/serde-yaml/commit/f668f71ea4c49eadb15926415c4b0c23a93ef9bc"><code>f668f71</code></a> Preserve location information better when parsing invalid tag</li>
<li>Additional commits viewable in <a href="https://github.com/dtolnay/serde-yaml/compare/0.9.19...0.9.21">compare view</a></li>
</ul>
</details>
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</details>

boa_tester/Cargo.toml

@@ -16,7 +16,7 @@ boa_engine = { workspace = true, features = ["annex-b"] }
 boa_gc.workspace = true
 clap = { version = "4.2.1", features = ["derive"] }
 serde = { version = "1.0.159", features = ["derive"] }
-serde_yaml = "0.9.19"
+serde_yaml = "0.9.21"
 serde_json = "1.0.95"
 bitflags = "2.1.0"
 regex = "1.7.3"