fix capacity

[wenshao]

What this PR does / why we need it?

Summary of your change

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 79.06977% with 9 lines in your changes missing coverage. Please review.

Project coverage is 74.82%. Comparing base (695f70f) to head (76c92c8).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...m/alibaba/fastjson2/support/csv/CSVWriterUTF8.java	60.00%	4 Missing and 2 partials ⚠️
.../alibaba/fastjson2/support/csv/CSVWriterUTF16.java	82.35%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3242      +/-   ##
============================================
+ Coverage     74.80%   74.82%   +0.01%     
- Complexity    23885    23900      +15     
============================================
  Files           668      668              
  Lines         92230    92238       +8     
  Branches      20623    20624       +1     
============================================
+ Hits          68997    69021      +24     
+ Misses        14978    14964      -14     
+ Partials       8255     8253       -2     

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