[Feature] Add diff seeds to diff ranks

[zytx121]

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Motivation

Add diff seeds to diff ranks. Refer to https://github.com/open-mmlab/mmselfsup/pull/228/files

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.

[yangxue0827]

LGTM

[codecov-commenter]

Codecov Report

Merging #102 (2df7a47) into dev (077ae5d) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev     #102      +/-   ##
==========================================
- Coverage   28.96%   28.94%   -0.02%     
==========================================
  Files         104      104              
  Lines        6581     6581              
  Branches      985      985              
==========================================
- Hits         1906     1905       -1     
  Misses       4609     4609              
- Partials       66       67       +1     

Flag	Coverage Δ
unittests	28.94% <ø> (ø)

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Impacted Files	Coverage Δ
mmrotate/datasets/builder.py	48.14% <0.00%> (-3.71%)	⬇️

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