ci: route github_release version parsing through env, not shell interpolation

[camgrimsec]

Proposed change

Follow-up in the same style as #11856 and #11857: move the one remaining ${{ ... }} expansion inside a run: body in github_release.yml into the step's env: block.

Before

- name: Delete next version rc0 tag in the CI environment
  run: |
    # Parse version X.Y.Z and increment Y for next minor version
    IFS='.' read -r MAJOR MINOR _ <<< "${{ steps.version.outputs.current_release }}"
    NEXT_MINOR=$((MINOR + 1))
    NEXT_TAG="v${MAJOR}.${NEXT_MINOR}.0-rc0"
    ...

After

- name: Delete next version rc0 tag in the CI environment
  env:
    CURRENT_RELEASE: ${{ steps.version.outputs.current_release }}
  run: |
    # Parse version X.Y.Z and increment Y for next minor version
    IFS='.' read -r MAJOR MINOR _ <<< "$CURRENT_RELEASE"
    NEXT_MINOR=$((MINOR + 1))
    NEXT_TAG="v${MAJOR}.${NEXT_MINOR}.0-rc0"
    ...

Two lines added (an env: header plus CURRENT_RELEASE:), one line changed ("$CURRENT_RELEASE" in place of the ${{ }} inside the here-string). One file touched.

Why

The value read here (steps.version.outputs.current_release) is produced by awk -F \\- '{print $1}' < VERSION.txt, so today the here-string is safe as long as VERSION.txt on the checked-out ref is well-formed. That's why this is a low-risk, mechanical change: it's the same pattern already used everywhere else in the release workflow after #11856 and #11857.

The reason to keep extending it here:

1. This step runs with contents: write (the job scope for ncipollo/release-action further down) and later invokes git tag -d "$NEXT_TAG". If anything ever makes it into VERSION.txt other than awk's first - field (a manual edit, a partial commit on a release branch, a mis-parsed prerelease format), an unexpected token would land directly in the shell body.
2. GitHub's security-hardening guide for GitHub Actions calls out this exact pattern (run: body reading a ${{ steps.*.outputs.* }} value) and recommends passing it through env:.
3. It closes the last template-injection hit for github_release.yml; every other ${{ ... }} in the file is already either in an env: block or an if: / with: field.

What is not changed

• The awk -F \\- '{print $1}' < VERSION.txt parsing step above.
• The IFS='.' read -r MAJOR MINOR _ split and the NEXT_MINOR = MINOR + 1 arithmetic.
• The NEXT_TAG format string.
• The subsequent git rev-parse --verify / git tag -d calls.
• The neighboring Generate release notes step, which already binds EARLIEST_VERSION via env:.

The tag that gets deleted, the branch it's deleted from, and the condition under which the step runs are all identical to the previous behavior.

Verification

• python3 -c "import yaml; yaml.safe_load(open('.github/workflows/github_release.yml'))" succeeds.
• Diff is 4 lines total (+3, -1) in one file.
• Every ${{ ... }} expression that previously appeared inside a run: body in this file is now bound at the step's env:.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings — N/A, this is a CI-only change with no runtime impact
• I've used one of the conventional commit types for my PR title
• I documented my code
• I ran pre-commit hooks and fixed any issue — N/A, YAML file, no code hooks apply

Thanks.

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