chore: fix gapic-libraries-bom format (#11807)

Co-authored-by: cloud-java-bot <cloud-java-bot@google.com>

Author: suztomo

gapic-libraries-bom/pom.xml

@@ -1410,4 +1410,4 @@
       </dependency>
     </dependencies>
   </dependencyManagement>
-</project>
+</project>