Update identity service app

[dingmeng-xue]

We can see below warning message during build. It's good to keep app up-to-date.

      /workspace/src/main/java/com/example/acme/identity/SecurityConfiguration.java:14: warning: [removal] oauth2ResourceServer() in ServerHttpSecurity has been deprecated and marked for removal
                httpSecurity.oauth2ResourceServer()
                            ^
      /workspace/src/main/java/com/example/acme/identity/SecurityConfiguration.java:15: warning: [removal] jwt() in ServerHttpSecurity.OAuth2ResourceServerSpec has been deprecated and marked for removal
                                        .jwt()
                                        ^