BUG: `df.agg` with kwargs

[ChengjieLi28]

What do these changes do?

Related issue number

Fixes #703

Check code requirements

• [x] tests added / passed (if needed)
• [x] Ensure all linting tests pass

[codecov[bot]]

Codecov Report

Merging #707 (7986879) into main (bb4c746) will increase coverage by 0.02%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #707      +/-   ##
==========================================
+ Coverage   93.50%   93.53%   +0.02%     
==========================================
  Files        1025     1025              
  Lines       79353    79353              
  Branches    16440    16440              
==========================================
+ Hits        74201    74220      +19     
+ Misses       3467     3444      -23     
- Partials     1685     1689       +4     

Flag	Coverage Δ
unittests	93.42% <100.00%> (+0.02%)	:arrow_up:

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

Files Changed	Coverage Δ
...n/xorbits/_mars/dataframe/reduction/aggregation.py	94.17% <100.00%> (+0.64%)	:arrow_up:

... and 5 files with indirect coverage changes