Upgrade 0Chain GoSDK to v1.8.12

[service-0chain]

0Chain GoSDK v1.8.12 is released.
see full changelog on https://github.com/0chain/gosdk/releases/tag/v1.8.12

[codecov-commenter]

Codecov Report

Merging #933 (8691088) into staging (21f8651) will not change coverage.
The diff coverage is n/a.

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@@           Coverage Diff            @@
##           staging     #933   +/-   ##
========================================
  Coverage    26.46%   26.46%           
========================================
  Files           77       77           
  Lines         7866     7866           
========================================
  Hits          2082     2082           
  Misses        5512     5512           
  Partials       272      272           

Flag	Coverage Δ
Unit-Tests	26.46% <ø> (ø)

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