fix: restore jdbc dependency

Reverts erroneous removal of this entry.

Author: diegomarquezp

google-cloud-bom/pom.xml

@@ -199,6 +199,11 @@
         <type>pom</type>
         <scope>import</scope>
       </dependency>
+      <dependency>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>google-cloud-spanner-jdbc</artifactId>
+        <version>2.35.5</version>
+      </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-vertexai-bom</artifactId>