Bump `Dockerfile.ci` (2024-09-09)
CI passed: https://github.com/NVIDIA/NeMo/actions/runs/10815035809 hey @akoumpa, some of these changes are definitely missing in the release branch `r2.0.0` (specifically, adding the attribute `fp8` to `ExampleConfig` of `tests/collections/llm/test_mnist_model_nemo2.py`

Can you help me figure out if this is the only change that we should cherry-pick, of its safer to cherry-pick the whole PR?
🚀 PR to Bump `Dockerfile.ci`.  

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

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