Provide more feedback from installation script

[lionello]

curl could fail for many reasons, but the error is currently swallowed. We should provide more feedback to the user, possibly including the actual error message, eg.

{"message":"API rate limit exceeded for 209.53.138.6. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)","documentation_url":"https://docs.github.com/rest/overview/resources-in-the-rest-api#rate-limiting"}  

See https://github.com/DefangLabs/defang/pull/638#discussion_r1733216072