Error during install on macOS

**Bug description**

I get an error during install script execution on macOS:

```
bash-3.2$ curl -fsSL https://raw.githubusercontent.com/game-ci/cli/main/install.sh | sh

info: Fetching installer: https://raw.githubusercontent.com/game-ci/cli/main/scripts/install.sh

info: Installing game-ci CLI (latest)
info: to: /Users/aas/.game-ci/bin

/var/folders/dj/2hhsb67s093gx0zh84qf4vzw0000gn/T/tmp.eoUI4APnrz/install.sh: line 116: auth_header[@]: unbound variable
error: Installation failed. See the output above for details.
```

**How to reproduce**

I run the command on my Mac Mini (Mac14,3), as instruced in `README.md`:

`curl -fsSL https://raw.githubusercontent.com/game-ci/cli/main/install.sh | sh`

- **Expected behavior**

Game-ci CLI should be installed successfully.

Start with scripts/install.sh, especially around line 116, and reproduce the documented curl command on macOS. Trace the auth_header[@] failure during installer execution; the work is done when the installer completes successfully and installs the game-ci CLI as described in the issue.

Written by the indexing model from the issue text.