Updated base64 to 0.21

[WindSoilder]

Hi, I found out that the dependency base64 is not up to date, which may cause some applications (like nushell) to compile it multiple times. It would be nice if base64 was updated and released without breaking semver compatibility in version numbers. Then our echo system will benefit from it too :) What do you think?

[codecov]

Codecov Report

Base: 83.61% // Head: 83.60% // Decreases project coverage by -0.01% ⚠️

Coverage data is based on head (64ba2fe) compared to base (ca7f36f).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1408      +/-   ##
==========================================
- Coverage   83.61%   83.60%   -0.01%     
==========================================
  Files         373      373              
  Lines       40288    40288              
==========================================
- Hits        33685    33683       -2     
- Misses       6603     6605       +2     

Impacted Files	Coverage Δ
src/io/parquet/read/schema/metadata.rs	82.85% <100.00%> (ø)
src/io/parquet/write/schema.rs	72.62% <100.00%> (ø)
src/array/utf8/mod.rs	83.98% <0.00%> (-1.18%)	⬇️
src/io/ipc/read/file.rs	96.42% <0.00%> (-0.90%)	⬇️
src/offset.rs	85.76% <0.00%> (-0.35%)	⬇️
src/bitmap/utils/slice_iterator.rs	98.78% <0.00%> (+1.21%)	⬆️
src/array/binary/mod.rs	94.08% <0.00%> (+1.47%)	⬆️

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