fix: resolve "invalid reference" error in contributors workflow (#12)

[Aryanbuha890]

🐛 Fixes #12

What was broken

After PR #11 merged, the contributors workflow failed every time with:

fatal: invalid reference: feat/issue-10-readme-contributors Error: Invalid status code: 128

Root Cause

On pull_request: closed events, GitHub checks out the merged PR's source branch
(e.g. feat/issue-10-readme-contributors) — not main. After the PR merges, that source
branch gets deleted. So when git-auto-commit-action tried to push a README update back
to that deleted branch ref, it failed with the invalid reference error.

---

Fix — 2 lines changed in .github/workflows/update-contributors.yml

Before:

- uses: actions/checkout@v4
  with:
    fetch-depth: 0          # ❌ checks out deleted PR source branch

- uses: stefanzweifel/git-auto-commit-action@v5
  with:
    commit_message: "docs: update contributors in README [skip ci]"
    file_pattern: "README.md"
                            # ❌ no branch specified → pushes to deleted ref


**After:**

- uses: actions/checkout@v4
  with:
    ref: main               # ✅ always checks out main
    fetch-depth: 0

- uses: stefanzweifel/git-auto-commit-action@v5
  with:
    commit_message: "docs: update contributors in README [skip ci]"
    file_pattern: "README.md"
    branch: main            # ✅ always commits back to main


**Expected Flow After Fix :**

PR merged into main
  → pull_request: closed fires
  → checkout ref: main ✅
  → Node script updates README.md
  → git-auto-commit-action commits to branch: main ✅
  → README updated, no errors in Actions log ✅

[github-actions]

🚨 @Aryanbuha890, pull requests modifying GitHub actions/workflows from forks are automatically closed for repository security. Maintainers will review and manually implement updates if needed.

[Aryanbuha890]

@udaycodespace Please check it and verify it, here i set the referene of main in this file for automate.

[udaycodespace]

@udaycodespace Please check it and verify it, here i set the referene of main in this file for automate.

I will review tonight!

[udaycodespace]

@Aryanbuha890 fix works, verified both lines. lgtm!

1. One thing though: write your own PR descriptions going forward.
2. Using AI to help is fine, but paste it as-is and it stops looking like your own understanding of the fix, that's why feat: automate README contributors section using GitHub Actions (#10) #11 got marked L1 instead of L2, not the code.
3. You're executing the assigned issues fine. Just own the write-up part too.