deps: update dependency com.google.cloud:google-cloud-spanner-bom to v2 (#884)

Author: renovate-bot

pom.xml

@@ -519,7 +519,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner-bom</artifactId>
-        <version>1.61.0</version>
+        <version>2.0.0</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>