Update protobuf to v4.28.0 (#35)

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

gradle/libs.versions.toml

@@ -3,7 +3,7 @@ grpc-java = "1.66.0"
 grpc-kotlin = "1.4.1"
 kotlin-core = "2.0.20"
 ktlint = "1.3.1"
-protobuf = "4.27.4"
+protobuf = "4.28.0"
 
 [libraries]
 assertk = { module = "com.willowtreeapps.assertk:assertk-jvm", version = "0.28.1" }