fix: declaring test-scope artifact as runtime (#1014)

Within this repository this dependency is only used in tests. However, making this test scope causes undeclared dependencies after the flatten-maven-plugin. Similar to googleapis/java-pubsub#1239

Author: suztomo

google-cloud-aiplatform/pom.xml

@@ -78,6 +78,17 @@
  <groupId>com.google.api.grpc</groupId>
  <artifactId>grpc-google-iam-v1</artifactId>
  </dependency>
+ <dependency>
+ <groupId>com.google.code.gson</groupId>
+ <artifactId>gson</artifactId>
+ <!--
+ Within this repository this dependency is only used in tests. However,
+ making this test scope causes undeclared dependencies after the
+ flatten-maven-plugin.
+ https://github.com/mojohaus/flatten-maven-plugin/issues/185
+ -->
+ <scope>runtime</scope>
+ </dependency>
 
  <!-- Test dependencies -->
  <dependency>
@@ -108,11 +119,6 @@
  <groupId>com.google.protobuf</groupId>
  <artifactId>protobuf-java-util</artifactId>
  </dependency>
- <dependency>
- <groupId>com.google.code.gson</groupId>
- <artifactId>gson</artifactId>
- <scope>test</scope>
- </dependency>
  </dependencies>
 
  <profiles>