Hi Bruno. I did some looking and it appears that the Spring Boot version used in the example is no longer available for download. I was able to specify a more recent version and successfully complete the step. Here is how I modified the command:
curl https://start.spring.io/starter.tgz -d type=maven-project -d dependencies=web,data-jpa,mysql -d baseDir=azure-spring-workshop -d bootVersion=3.4.3 -d javaVersion=17 | tar -xzvf -
Hope this helps!