Set User-Agent header when making requests against api.spring.io

Closes gh-1635

start-site/src/main/java/io/spring/start/site/StartApplication.java

@@ -36,8 +36,10 @@
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpHeaders;
 import org.springframework.scheduling.annotation.EnableAsync;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.RestTemplate;
 
 /**
  * Initializr website application.
@@ -64,7 +66,9 @@ public HomeController homeController() {
 	@Bean
 	public StartInitializrMetadataUpdateStrategy initializrMetadataUpdateStrategy(
 			RestTemplateBuilder restTemplateBuilder, ObjectMapper objectMapper) {
-		return new StartInitializrMetadataUpdateStrategy(restTemplateBuilder.build(), objectMapper);
+		RestTemplate restTemplate = restTemplateBuilder.defaultHeader(HttpHeaders.USER_AGENT, "start.spring.io")
+			.build();
+		return new StartInitializrMetadataUpdateStrategy(restTemplate, objectMapper);
 	}
 
 	@Bean