Upgrade to protobuf-gradle-plugin 0.9.3

- Add a fix for users of this plugin to call correct
  sourceSets object as it is now shadowed by protobuf extension
  getSourceSets
  https://github.com/google/protobuf-gradle-plugin/blame/master/src/main/groovy/com/google/protobuf/gradle/ProtobufExtension.groovy#L75
- Pulls in a fix for https://github.com/google/protobuf-gradle-plugin/issues/687

Test: ./gradlew bOS --dry-run
Change-Id: Id1c0a7e809e7067933be260c51a68140990db78e
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 3431ba0..abfe27d 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -236,7 +236,7 @@
 paparazziNativeMacOsX64 = { module = "app.cash.paparazzi:layoutlib-native-macosx", version.ref = "paparazziNative" }
 protobuf = { module = "com.google.protobuf:protobuf-java", version.ref = "protobuf" }
 protobufCompiler = { module = "com.google.protobuf:protoc", version.ref = "protobuf" }
-protobufGradlePluginz = { module = "com.google.protobuf:protobuf-gradle-plugin", version = "0.9.0" }
+protobufGradlePluginz = { module = "com.google.protobuf:protobuf-gradle-plugin", version = "0.9.3" }
 protobufLite = { module = "com.google.protobuf:protobuf-javalite", version.ref = "protobuf" }
 protobufKotlin = { module = "com.google.protobuf:protobuf-kotlin", version.ref = "protobuf" }
 reactiveStreams = { module = "org.reactivestreams:reactive-streams", version = "1.0.0" }