The GH_TOKEN env var is used by the gh CLI (for PR creation, issue creation, etc.), but git push doesn't read it. Git needs credentials configured through either a credential helper or a token embedded in the remote URL. The error message "Invalid username or token. Password authentication is not supported" confirms that git was falling back to plain password auth, which GitHub no longer supports.
The fix replaces the remote URL with one that includes the GITHUB_TOKEN as an x-access-token — this is the standard pattern for authenticating git operations in GitHub Actions. I also removed the unnecessary GH_TOKEN env var from this step since it doesn't use gh.
2026-02-25
"Dunder" (short for "double underscore") refers to special methods in Python, also known as "magic methods," surrounded by double underscores (e.g., init, str). They define default behavior for user-defined objects, such as operator overloading, object initialization, and string representation