Update New Features in V0.2.7

[Lupin1998]

Updateing new features:

• Refactor mixup_classification.py to support label mixup methods, add return_mask for mixup methods in augments and add return_attn in ViT backbone.
• Support a new mixup method TransMix and provide config files in mixups/deit.
• Update config files. Provide full config files of mixup methods based on ViT-T/S/B on ImageNet and update RSB A3 config files for popular backbones.
• Refine the setup for the local installation and PyPi release in setup.py and setup.cfg. View PyPi project of OpenMixup.

[Lupin1998]

• Refine the setup for the local installation and PyPi release in setup.py and setup.cfg. View PyPi project of OpenMixup (commit https://github.com/Westlake-AI/openmixup/commit/baece8ee07d9820363c06a387d943c0f8a5a02a8).