Bump protobuf-java from 3.20.1 to 3.21.4 (#3957)

Summary:
Bumps [protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.20.1 to 3.21.4.
<details>
<summary>Commits</summary>
<ul>
<li><a href="c9869dc780"><code>c9869dc</code></a> Updating version.json and repo version numbers to: 21.4</li>
<li><a href="c2548258b9"><code>c254825</code></a> Reduce the required alignment of ArenaString from 8 to 4 (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10298">#10298</a>)</li>
<li><a href="ddb21b2dff"><code>ddb21b2</code></a> Update version.json to: 21.4-dev (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10299">#10299</a>)</li>
<li><a href="4e7c56cf43"><code>4e7c56c</code></a> Update developer username in package.xml (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10297">#10297</a>)</li>
<li><a href="e7835368be"><code>e783536</code></a> Update the release date in package.xml (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10295">#10295</a>)</li>
<li><a href="4d2d935f6c"><code>4d2d935</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10289">#10289</a> from protocolbuffers/21.x-202207202258</li>
<li><a href="b1eb1260fc"><code>b1eb126</code></a> Updating version.json and repo version numbers to: 21.3</li>
<li><a href="00253761b2"><code>0025376</code></a> Upgrade upb and update CHANGES.txt (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10286">#10286</a>)</li>
<li><a href="c8b4ef27a0"><code>c8b4ef2</code></a> [Bazel] Add back a filegroup for :well_known_protos (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10279">#10279</a>)</li>
<li><a href="f049e5f029"><code>f049e5f</code></a> Update version.json to: 21.3-dev (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/10275">#10275</a>)</li>
<li>Additional commits viewable in <a href="https://github.com/protocolbuffers/protobuf/compare/v3.20.1...v3.21.4">compare view</a></li>
</ul>
</details>
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</details>

Pull Request resolved: https://github.com/facebook/flipper/pull/3957

Reviewed By: passy

Differential Revision: D38315196

Pulled By: LukeDefeo

fbshipit-source-id: 80b2d2beb44bcbc4338ce1a8fa6270c18ce37ab8

build.gradle

@@ -99,7 +99,7 @@ ext.deps = [
         okhttp3            : 'com.squareup.okhttp3:okhttp:4.9.3',
         leakcanary         : 'com.squareup.leakcanary:leakcanary-android:1.6.3',
         leakcanary2        : 'com.squareup.leakcanary:leakcanary-android:2.8.1',
-        protobuf           : 'com.google.protobuf:protobuf-java:3.20.1',
+        protobuf           : 'com.google.protobuf:protobuf-java:3.21.4',
         testCore           : 'androidx.test:core:1.4.0',
         testRules          : 'androidx.test:rules:1.4.0',
         // Plugin dependencies