Merge pull request #284 from android/renovate/protobuf

Update protobuf to v3.21.9

Author: mmoczkowski

gradle/libs.versions.toml

@@ -39,7 +39,7 @@ kotlinxSerializationJson = "1.4.0"
 ksp = "1.7.20-1.0.6"
 lint = "30.2.2"
 okhttp = "4.10.0"
-protobuf = "3.21.5"
+protobuf = "3.21.9"
 protobufPlugin = "0.8.19"
 retrofit = "2.9.0"
 retrofitKotlinxSerializationJson = "0.8.0"