chore(java-storage-nio): modernize submodule pom.xml

Author: suztomo

java-storage-nio/google-cloud-nio-retrofit/pom.xml

@@ -5,7 +5,7 @@
   <version>0.128.14</version><!-- {x-version-update:google-cloud-nio:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud NIO Retrofit Example</name>
-  <url>https://github.com/googleapis/java-storage-nio</url>
+  <url>https://github.com/googleapis/google-cloud-java</url>
   <description>
     Demonstrates how to use the google-cloud-nio jar to add Google Cloud Storage functionality to legacy code.
   </description>