Bump up events-broker to 3.4-rc0

Change-Id: I7378e9b36acfed4835aa977b54a229c9306c4c19
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 09663e8..63b890d 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -16,8 +16,8 @@
 
     maven_jar(
         name = "events-broker",
-        artifact = "com.gerritforge:events-broker:3.1.4",
-        sha1 = "5672908dde0bd02cabc95efe34a8d8507d44b6ac",
+        artifact = "com.gerritforge:events-broker:3.4.0-rc0",
+        sha1 = "8c34c88103d4783eb4c4decde6d93541bc1cf064",
     )
 
     maven_jar(