Your project needs a different version of Carthage that is on our currently available stacks.
There are two cases we can look at:
You need to update Carthage to the latest version:
You can upgrade the preinstalled Carthage version with a Script Step (just add the Script Step before Carthage would be used in your build):
#!/bin/bash set -ex brew upgrade carthage
You need a specific version that is not the latest version:
This is a bit more complicated, as Homebrew does not support installing a specific version normally. You need to point a specific revision of Carthage available on Homebrew's git repository. For example:
brew install https://github.com/Homebrew/homebrew-core/raw/6d42f6048c327300c2969e23e06f75dd061ad34b/Formula/carthage.rb