[Enhancement] Delete DS_Store file

[MeowZheng]

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

As title

Modification

1. Remove DS_Store
2. Add DS_Store in gitignore

BC-breaking (Optional)

Does the modification introduce changes that break the backward-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. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDet or MMDet3D.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[codecov]

Codecov Report

Merging #1549 (6890aa5) into master (bc60213) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1549   +/-   ##
=======================================
  Coverage   90.40%   90.40%           
=======================================
  Files         141      141           
  Lines        8443     8443           
  Branches     1423     1423           
=======================================
  Hits         7633     7633           
  Misses        572      572           
  Partials      238      238           

Flag	Coverage Δ
unittests	90.40% <ø> (ø)

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

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bc60213...6890aa5. Read the comment docs.