improve: use version-tagged GitHub Action refs in CI workflow

[Coding-Dev-Tools]

Automated improvement by dev-engineer.

[github-actions]

🤖 Automated Code Review

✅ Ruff Lint — No issues

⚠️ Ruff Format — Formatting needed

Would reformat: src/json2sql/cli.py
Would reformat: src/json2sql/converter.py
Would reformat: tests/test_cli.py
Would reformat: tests/test_converter.py
Would reformat: tests/test_dialects.py
Would reformat: tests/test_remaining_coverage.py
6 files would be reformatted, 4 files already formatted

✅ Secret Detection — Clean

✅ Large Files — Within limits

📊 Diff Stats — 2 file(s) changed

 .github/workflows/ci.yml | 4 ++--
 src/json2sql/cli.py      | 8 +++++---
 2 files changed, 7 insertions(+), 5 deletions(-)

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Verdict: ⚠️ Warnings — Lint/format issues found. Recommend fixing before merge.

Automated by Coding-Dev-Tools/.github reusable workflow.