chore(beep boop 🤖): Bump `MCORE_TAG=ca87dcd...` (2024-12-21)
🚀 PR to bump `NVIDIA/Megatron-LM` in `Dockerfile.ci` to `MCORE_TAG=ca87dcd69727f9d436956a438733b994d13bba44`.  

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

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