Bump serde_yaml from 0.9.19 to 0.9.21 in /packer (#4664)

Summary:
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="8057faddd6"><code>8057fad</code></a> Release 0.9.21</li>
<li><a href="19a7bd3d9b"><code>19a7bd3</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/371">https://github.com/facebook/flipper/issues/371</a> from dtolnay/emptytag</li>
<li><a href="ebb4b7af3a"><code>ebb4b7a</code></a> Fix deserialization of tag !&lt;%21&gt;</li>
<li><a href="879a57fe91"><code>879a57f</code></a> Factor out conversion function from libyaml Tag to tag string</li>
<li><a href="e3b9a02a13"><code>e3b9a02</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/370">https://github.com/facebook/flipper/issues/370</a> from dtolnay/emptytag</li>
<li><a href="ef435495d1"><code>ef43549</code></a> Treat Tag::new(&quot;!&quot;) as tag %21, instead of empty tag</li>
<li><a href="221154cc1b"><code>221154c</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/369">https://github.com/facebook/flipper/issues/369</a> from dtolnay/emptytag</li>
<li><a href="39a866c695"><code>39a866c</code></a> Reuse Tag visitor in Value's Deserialize impl</li>
<li><a href="80e53a5166"><code>80e53a5</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/serde-yaml/issues/368">https://github.com/facebook/flipper/issues/368</a> from dtolnay/emptytag</li>
<li><a href="f668f71ea4"><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>
<br />

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</details>

Pull Request resolved: https://github.com/facebook/flipper/pull/4664

Reviewed By: ivanmisuno

Differential Revision: D44995834

Pulled By: passy

fbshipit-source-id: dca70186444985211f298b9c4769db2343694da3

packer/Cargo.lock

@@ -661,9 +661,9 @@ dependencies = [
 
 [[package]]
 name = "serde_yaml"
-version = "0.9.19"
+version = "0.9.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f82e6c8c047aa50a7328632d067bcae6ef38772a79e28daf32f735e0e4f3dd10"
+checksum = "d9d684e3ec7de3bf5466b32bd75303ac16f0736426e5a4e0d6e489559ce1249c"
 dependencies = [
  "indexmap",
  "itoa",

packer/Cargo.toml

@@ -14,7 +14,7 @@ clap = { version = "^3", features = ["derive", "cargo"] }
 shellexpand = "^2"
 tar = "0.4.38"
 serde = { version = "^1", features = ["derive"] }
-serde_yaml = "0.9.19"
+serde_yaml = "0.9.21"
 anyhow = "^1"
 sha2 = "0.10.6"
 data-encoding = "^2"