Auto-update dependencies. (GoogleCloudPlatform#941)

Author: dpebot

dataflow/spanner-io/pom.xml

@@ -78,7 +78,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>0.20.0-beta</version>
+      <version>0.30.0-beta</version>
     </dependency>
 
     <!-- Misc -->