Bump protobuf.version from 3.15.2 to 3.15.3 (#1261)

Bumps `protobuf.version` from 3.15.2 to 3.15.3.

Updates `protobuf-java` from 3.15.2 to 3.15.3
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/master/generate_changelog.py)
- [Commits](protocolbuffers/protobuf@v3.15.2...v3.15.3)

Updates `protobuf-java-util` from 3.15.2 to 3.15.3
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/master/generate_changelog.py)
- [Commits](protocolbuffers/protobuf@v3.15.2...v3.15.3)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

pom.xml

@@ -126,7 +126,7 @@
         <avro.version>1.10.1</avro.version>
         <json-schema-validator.version>1.0.49</json-schema-validator.version>
         <wire-schema.version>3.2.2</wire-schema.version>
-        <protobuf.version>3.15.2</protobuf.version>
+        <protobuf.version>3.15.3</protobuf.version>
         <xmlsec.version>2.1.5</xmlsec.version>
         <wsdl4j.version>1.6.3</wsdl4j.version>