Add secret manager to spring-cloud-gcp dependency versions (spring-attic#2187)

Add the secret manager starter to the spring-cloud-gcp dependency management.

Author: dzou

spring-cloud-gcp-dependencies/pom.xml

@@ -180,6 +180,11 @@
 				<artifactId>spring-cloud-gcp-starter-bigquery</artifactId>
 				<version>${project.version}</version>
 			</dependency>
+			<dependency>
+				<groupId>org.springframework.cloud</groupId>
+				<artifactId>spring-cloud-gcp-starter-secretmanager</artifactId>
+				<version>${project.version}</version>
+			</dependency>
 
 			<!-- spring-cloud-gcp-starter-sql -->
 			<dependency>