Remove the use of anyhow in EncodeError

[cathay4t]

Changed EncodeError from struct to enum and remove the use of
anyhow but using thiserror instead.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 35.08%. Comparing base (414d14e) to head (75214bb).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/errors.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #21      +/-   ##
==========================================
+ Coverage   34.60%   35.08%   +0.47%     
==========================================
  Files           3        3              
  Lines         367      362       -5     
==========================================
  Hits          127      127              
+ Misses        240      235       -5     

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