feat: add serialization to base64

[hanxiao]

No description provided.

[codecov]

Codecov Report

Merging #33 (677b597) into main (3a906db) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #33      +/-   ##
==========================================
+ Coverage   83.18%   83.26%   +0.07%     
==========================================
  Files          67       67              
  Lines        3135     3149      +14     
==========================================
+ Hits         2608     2622      +14     
  Misses        527      527              

Flag	Coverage Δ
docarray	83.26% <100.00%> (+0.07%)	⬆️

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Impacted Files	Coverage Δ
docarray/array/mixins/io/binary.py	95.55% <100.00%> (+0.31%)	⬆️
docarray/document/mixins/porting.py	92.59% <100.00%> (+0.92%)	⬆️
docarray/proto/io/ndarray.py	94.78% <100.00%> (+0.09%)	⬆️

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