Set e2cnn as an optional dependency

[zytx121]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

open-mmlab/mmyolo#513

• Only ReDet use e2cnn, so we set it as an optional dependency.
• Unlimit numpy version.

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the back-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. The documentation has been modified accordingly, like docstring or example tutorials.

[codecov]

Codecov Report

Base: 61.90% // Head: 79.37% // Increases project coverage by +17.47% 🎉

Coverage data is based on head (d8aef1e) compared to base (4922856).
Patch coverage: 41.86% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##           dev-1.x     #724       +/-   ##
============================================
+ Coverage    61.90%   79.37%   +17.47%     
============================================
  Files          100      100               
  Lines         7239     7272       +33     
  Branches      1039     1039               
============================================
+ Hits          4481     5772     +1291     
+ Misses        2507     1162     -1345     
- Partials       251      338       +87     

Flag	Coverage Δ
unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmrotate/models/utils/__init__.py	100.00% <ø> (ø)
mmrotate/models/backbones/re_resnet.py	82.97% <40.90%> (-3.91%)	⬇️
mmrotate/models/necks/re_fpn.py	80.64% <41.17%> (-5.18%)	⬇️
mmrotate/models/utils/enn.py	90.00% <50.00%> (-4.60%)	⬇️
mmrotate/evaluation/metrics/dota_metric.py	87.00% <0.00%> (-1.13%)	⬇️
mmrotate/models/task_modules/coders/angle_coder.py	44.55% <0.00%> (+0.99%)	⬆️
mmrotate/models/dense_heads/rotated_rtmdet_head.py	64.85% <0.00%> (+3.19%)	⬆️
mmrotate/models/dense_heads/rotated_fcos_head.py	71.31% <0.00%> (+3.68%)	⬆️
mmrotate/testing/_utils.py	83.62% <0.00%> (+5.17%)	⬆️
.../task_modules/assigners/rotate_iou2d_calculator.py	67.36% <0.00%> (+5.26%)	⬆️
... and 24 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[liuyanyi]

LGTM

[RangiLyu]

The latest e2cnn has supported the new numpy version. You can upgrade the requirement file like this https://github.com/open-mmlab/mmrotate/pull/713/files

[zytx121]

The latest e2cnn has supported the new numpy version. You can upgrade the requirement file like this https://github.com/open-mmlab/mmrotate/pull/713/files

Done.