chore(beep boop 🤖): Bump `MCORE_TAG=076972e...` (2024-12-31)
🚀 PR to bump `NVIDIA/Megatron-LM` in `Dockerfile.ci` to `MCORE_TAG=076972e37420b5325c5fe06e7131be7d96f05b53`.  

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

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