bug(rpc): duplicated error from the uber.multierr

[rustatian]

Reason for This PR

closes: #128

Description of Changes

• Remove uber.multierr package
• Use our errors

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the MIT license.

PR Checklist

[Author TODO: Meet these criteria.]
[Reviewer TODO: Verify that these criteria are met. Request changes if not]

• All commits in this PR are signed (git commit -s) or (git commit -S).
• The reason for this PR is clearly provided (issue no. or explanation).
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• Any user-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.

[codecov]

Codecov Report

Merging #129 (24b2036) into master (b67b3b1) will increase coverage by 0.36%.
The diff coverage is 45.45%.

@@            Coverage Diff             @@
##           master     #129      +/-   ##
==========================================
+ Coverage   56.64%   57.01%   +0.36%     
==========================================
  Files           9        9              
  Lines         542      542              
==========================================
+ Hits          307      309       +2     
+ Misses        202      201       -1     
+ Partials       33       32       -1     

Impacted Files	Coverage Δ
pkg/rpc/codec.go	64.00% <45.45%> (+1.60%)	⬆️

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