[Enhance] Set torch seed in worker_init_fn

[mzr1996]

Motivation

If random function of PyTorch is used in pipeline, we need to set torch seed in work_init_fn.

Modification

As the title.

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects, like MMDet or MMSeg.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Merging #733 (361b25f) into dev (2037260) will increase coverage by 0.09%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##              dev     #733      +/-   ##
==========================================
+ Coverage   84.93%   85.03%   +0.09%     
==========================================
  Files         121      123       +2     
  Lines        7549     7604      +55     
  Branches     1303     1311       +8     
==========================================
+ Hits         6412     6466      +54     
- Misses        945      946       +1     
  Partials      192      192              

Flag	Coverage Δ
unittests	84.95% <0.00%> (+0.09%)	⬆️

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

Impacted Files	Coverage Δ
mmcls/datasets/builder.py	91.04% <0.00%> (-1.38%)	⬇️
mmcls/datasets/__init__.py	100.00% <0.00%> (ø)
mmcls/models/utils/augment/__init__.py	100.00% <0.00%> (ø)
mmcls/models/utils/augment/resizemix.py	100.00% <0.00%> (ø)
mmcls/datasets/cub.py	100.00% <0.00%> (ø)

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[Ezra-Yu]

LGTM.