Increment the jdbc driver version for the Hibernate sample. (GoogleCloudPlatform#1796)

Author: dzou

spanner/hibernate/pom.xml

@@ -37,7 +37,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner-jdbc</artifactId>
-      <version>1.11.0</version>
+      <version>1.12.0</version>
     </dependency>
 
     <!-- Hibernate core dependency -->