chore(beep boop 🤖): Bump `MCORE_TAG=a9d040c...` (2024-11-23)
🚀 PR to bump `NVIDIA/Megatron-LM` in `Dockerfile.ci` to `MCORE_TAG=a9d040c355f7f2d3ead209931cd95d61167494fa`.  

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

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