Upgrade maven invoker in spring-boot-samples-invoker

[philwebb]

The cloneProjectsTo issue is fixed so when 3.1.0 is released we can remove the work-around.

[davidhgray]

what does "status: blocked" mean? is it ok to commit and create pull requests for blocked issues?

[wilkinsona]

what does "status: blocked" mean?

It means that no progress can be made on the issue due to something that's out of our control. In this case, we're waiting for Maven Invoker Plugin 3.0.2 to be released.

is it ok to commit and create pull requests for blocked issues?

That will only be possible if the issue's actually no longer blocked but we haven't noticed and haven't removed the label.