Bump protobuf-java from 3.15.7 to 3.15.8

Bumps [protobuf-java](https://github.com/protocolbuffers/protobuf) from 3.15.7 to 3.15.8.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/master/generate_changelog.py)
- [Commits](protocolbuffers/protobuf@v3.15.7...v3.15.8)

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -74,7 +74,7 @@
         <jmeter.version>5.4.1</jmeter.version>
         <micrometer-jvm-extras.version>0.2.2</micrometer-jvm-extras.version>
         <msgpack.version>0.8.22</msgpack.version>
-        <protobuf.version>3.15.7</protobuf.version>
+        <protobuf.version>3.15.8</protobuf.version>
         <release.version>0.31.0-rc1</release.version> <!-- Used to replace release versions in all files -->
         <release.chartVersion>0.18.0-rc1</release.chartVersion>
         <replacer.version>1.5.3</replacer.version>