http-service: re add version for spring-boot-maven-plugin

Plugin dependency versions are not imported from import scoped
dependencies in dependencyManagement

http-service/pom.xml

@@ -164,6 +164,7 @@
 			<plugin>
 				<groupId>org.springframework.boot</groupId>
 				<artifactId>spring-boot-maven-plugin</artifactId>
+				<version>${spring.boot.version}</version>
 			</plugin>
 			<plugin>
 				<groupId>org.apache.tomcat.maven</groupId>