chore: declaring pom type for google-api-client-assembly (#1690)

Fixes #1686

Author: suztomo

google-api-client-bom/pom.xml

@@ -79,6 +79,7 @@
         <groupId>com.google.api-client</groupId>
         <artifactId>google-api-client-assembly</artifactId>
         <version>1.31.2</version><!-- {x-version-update:google-api-client:current} -->
+        <type>pom</type>
       </dependency>
       <dependency>
         <groupId>com.google.api-client</groupId>