Fix Schema Registry tests by adding restclient dependency

Author: olegz

schema-registry/spring-cloud-stream-schema-registry-server/pom.xml

@@ -44,6 +44,11 @@
 			<!--TODO: investigate why we need this hard version here and not inheriting from Spring Boot-->
 			<version>2.15.3</version>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-restclient</artifactId>
+			<scope>test</scope>
+		</dependency>
     </dependencies>