chore(beep boop 🤖): Bump `MCORE_TAG=67a50f2...` (2024-11-29)
🚀 PR to bump `NVIDIA/Megatron-LM` in `Dockerfile.ci` to `MCORE_TAG=67a50f2f9b2f12b1361ac0f21fc3410b23e07d5e`.  

📝 Please remember the following to-do's before merge: 
- [ ] Verify the presubmit CI  

🙏 Please merge this PR only if the CI workflow completed successfully.