Issue 678: Add EfficientNet

[SicongluUCL]

Description

Implemented 3D EfficientNet for Deepreg

Fixes #678

Type of change

What types of changes does your code introduce to DeepReg?

Please check the boxes that apply after submitting the pull request.

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Documentation Update (fix or improvement on the documentation)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Other (if none of the other choices apply)

Checklist

Please check the boxes that apply after submitting the pull request.

If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [ ] I have installed pre-commit using pre-commit install and formatted all changed files. If you are not certain, run pre-commit run --all-files.
• [x] My commits' message styles matches our requested structure, e.g. Issue #<issue number>: detailed message.
• [ ] I have updated the change log file regarding my changes.
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)

[mathpluscode]

Hi @SicongluUCL, could you update this PR regarding the comments? I feel like it's not updated?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.