Bump protobuf-java from 3.15.6 to 3.15.8 (#2181)

Summary:
Bumps [protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.15.6 to 3.15.8.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/protocolbuffers/protobuf/releases">protobuf-java's releases</a>.</em></p>
<blockquote>
<h2>Protocol Buffers v3.15.8</h2>
<h1>Ruby</h1>
<ul>
<li>Fixed memory leak of Ruby arena objects (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8461">#8461</a>)</li>
</ul>
<h2>Protocol Buffers v3.15.7</h2>
<h1>C++</h1>
<ul>
<li>Remove the ::pb namespace (alias) (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8423">#8423</a>)</li>
</ul>
<h1>Ruby</h1>
<ul>
<li>Fix unbounded memory growth for Ruby &lt;2.7 (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8429">#8429</a>)</li>
<li>Fixed message equality in cases where the message type is different (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8434">#8434</a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="436bd7880e"><code>436bd78</code></a> Updated version to 3.15.8 (<a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8463">#8463</a>)</li>
<li><a href="1ed9a8b521"><code>1ed9a8b</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8461">#8461</a> from haberman/ruby-arena-memory-leak</li>
<li><a href="67fee915e0"><code>67fee91</code></a> Fixed memory leak of Ruby arena objects.</li>
<li><a href="878be3569e"><code>878be35</code></a> Update protobuf version</li>
<li><a href="c00c2d43bb"><code>c00c2d4</code></a> Updated CHANGES.txt and package.xml with changes for 3.15.7</li>
<li><a href="240e54efe5"><code>240e54e</code></a> Remove references to stale benchmark data sources.</li>
<li><a href="f3f8707ba5"><code>f3f8707</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8434">#8434</a> from haberman/ruby-message-eq</li>
<li><a href="38e1b59258"><code>38e1b59</code></a> Elided the TYPE() and msgdef checks by using CLASS_OF.</li>
<li><a href="d69f482883"><code>d69f482</code></a> Fixed message equality in cases where the message type is different.</li>
<li><a href="a38319b5c4"><code>a38319b</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/protocolbuffers/protobuf/issues/8429">#8429</a> from haberman/ruby-gc-secondarymap</li>
<li>Additional commits viewable in <a href="https://github.com/protocolbuffers/protobuf/compare/v3.15.6...v3.15.8">compare view</a></li>
</ul>
</details>
<br />

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</details>

Pull Request resolved: https://github.com/facebook/flipper/pull/2181

Reviewed By: mweststrate

Differential Revision: D27945999

Pulled By: passy

fbshipit-source-id: 3232dd26a5528995f0d9858c388fa1bfdf5cc8a9

build.gradle

@@ -102,7 +102,7 @@ ext.deps = [
         okhttp3            : 'com.squareup.okhttp3:okhttp:4.9.1',
         leakcanary         : 'com.squareup.leakcanary:leakcanary-android:1.6.3',
         leakcanary2        : 'com.squareup.leakcanary:leakcanary-android:2.6',
-        protobuf           : 'com.google.protobuf:protobuf-java:3.15.6',
+        protobuf           : 'com.google.protobuf:protobuf-java:3.15.8',
         testCore           : 'androidx.test:core:1.3.0',
         testRules          : 'androidx.test:rules:1.3.0',
         // Plugin dependencies