Update Spring Authorization Server sample to Spring Boot 2.7.2

servlet/spring-boot/java/oauth2/authorization-server/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-	id 'org.springframework.boot' version '2.6.4'
+	id 'org.springframework.boot' version '2.7.2'
 	id 'io.spring.dependency-management' version '1.0.11.RELEASE'
 	id "nebula.integtest" version "8.2.0"
 	id 'java'