chore(deps): update dependency com.google.cloud:google-cloud-notification to v0.121.3-beta (#204)

Author: renovate-bot

notification/snippets/pom.xml

@@ -40,7 +40,7 @@
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-notification</artifactId>
       <!-- TODO: REMOVE VERSION SPECIFIED BELOW WHEN THE CLIENT GOES GA-->
-      <version>0.121.2-beta</version>
+      <version>0.121.3-beta</version>
     </dependency>
 
     <dependency>