Make sure envs created during steps are also recognized

**Is your feature request related to a problem? Please describe.**

As shown below, the value of GITHUB_ENV created during execution is not recognized by extention.
However, since this method is officially recommended by GitHub https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-environment-variable I think the created env should also be able to recognize it.

**Describe the solution you'd like**
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**Additional context**
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Start by reproducing a workflow that writes an environment variable through GITHUB_ENV during execution, then trace where the extension recognizes workflow environments. Done means variables created by steps using the documented GITHUB_ENV method are recognized by the extension.

索引モデルが issue の本文から書いたものです。