Bump protobuf.version from 3.21.10 to 4.26.1 (#633)

Bumps `protobuf.version` from 3.21.10 to 4.26.1.

Updates `com.google.protobuf:protobuf-bom` from 3.21.10 to 4.26.1
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

Updates `com.google.protobuf:protobuf-java-util` from 3.21.10 to 4.26.1

---
updated-dependencies:
- dependency-name: com.google.protobuf:protobuf-bom
  dependency-type: direct:production
  update-type: version-update:semver-major
- dependency-name: com.google.protobuf:protobuf-java-util
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

formats/protobuf/pom.xml

@@ -32,7 +32,7 @@
     <packaging>jar</packaging>
 
     <properties>
-        <protobuf.version>4.31.1</protobuf.version>
+        <protobuf.version>4.34.1</protobuf.version>
         <module-name>io.cloudevents.formats.protobuf</module-name>
     </properties>