Add a check to skip `cmatrix` installation if running in a GitHub Codespace.
* **Check for GitHub Codespace**: Add a check for the `CODESPACES` environment variable at the beginning of the script.
* **Skip Installation**: Skip the installation of `cmatrix` if the `CODESPACES` environment variable is set.
* **Informative Message**: Add a message indicating that the installation is being skipped due to running in a GitHub Codespace.
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