chore: skip writing to GITHUB_ENV when building formula

[SpiffyEight77]

Description

chore: skip writing to GITHUB_ENV when building formula

Issue

I'm working on the add brew tap for porter #3045, It appears that the CI process in homebrew-core does not permit writing to GITHUB_ENV.

This restriction leads to a panic when building formulas.

As a workaround, I skip writing to GITHUB_ENV when building formulas by detecting whether the repository is Homebrew/homebrew-core.

[kichristensen]

@SpiffyEight77 Thanks for the PR. It looks good to me. Have you been able to test that it works with this change in Homebrew?

[SpiffyEight77]

@SpiffyEight77 Thanks for the PR. It looks good to me. Have you been able to test that it works with this change in Homebrew?

@kichristensen
Thank you for your response.

I've tested it in the homebrew-core CI, and it has passed the formula building step.

Once this PR is merged and the formula submission for porter is complete, I'd like to explore how to inject an environment variable into the Trivy CI(It seems that the environment variable version will be used.) to make it more flexible.

[kichristensen]

@schristoff It looks good to me, but you might have some insights into the different flows used?

[schristoff]

😶‍🌫️ I'm 50/50 if this will break CI, but I don't think so since we moved to GHA. If it does, we will deal with it in Porter main.