fix: set http response chartset to utf-8 when using table format

[xxxuuu]

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fixed the problem mentioned in this PR: #3539

What's changed and what's your intention?

The table format contains non-ASCII characters, and the content-type does not specify a character set. Although most clients will try to using UTF-8, but we cannot make this assumption and need to explicitly set it.

before:

after:

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.06%. Comparing base (1f0fc40) to head (5f92712).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3571      +/-   ##
==========================================
- Coverage   85.36%   85.06%   -0.31%     
==========================================
  Files         910      911       +1     
  Lines      152033   152425     +392     
==========================================
- Hits       129784   129661     -123     
- Misses      22249    22764     +515     

[tisonkun]

Thanks for following up!

Merging ..