Update protobuf to v4.28.0 (#137)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

gradle/libs.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 grpc = "1.66.0"
-protobuf = "4.27.4"
+protobuf = "4.28.0"
 
 [libraries]
 protobuf = { module = "com.google.protobuf:protobuf-java", version.ref = "protobuf" }