chore(beep boop 🤖): Bump `MCORE_TAG=844119f...` (2024-12-04)
🚀 PR to bump `NVIDIA/Megatron-LM` in `Dockerfile.ci` to `MCORE_TAG=844119f5c856a3037ec7c7f6d6ef7b3518ceee6b`.  

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

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