Remove Ming Qiu from maintainers

[qiuming-best]

Thank you for contributing to Velero!

Please add a summary of your change

Removing myself from the maintainers list.

Does your change fix a particular issue?

Fixes #(issue)

Please indicate you've done the following:

• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.94%. Comparing base (ec2013b) to head (677d99a).
Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8411      +/-   ##
==========================================
- Coverage   58.95%   58.94%   -0.01%     
==========================================
  Files         367      367              
  Lines       38902    38926      +24     
==========================================
+ Hits        22933    22945      +12     
- Misses      14507    14518      +11     
- Partials     1462     1463       +1     

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