The repository cannot be fetched
It seems that you specified a repository URL using SSH. You need to setup a SSH key on Symfony Insight and allow it on your SCM server.
Also check the following possible causes:Cloning into '/tmp/project/code'...
Warning: Permanently added 'github.com' (ED25519) to the list of known hosts.
warning: Could not find remote branch dependabot/composer/phpstan/phpstan-1.12.8 to clone.
fatal: Remote branch dependabot/composer/phpstan/phpstan-1.12.8 not found in upstream origin