chore: remove deprecated Go Report badge with Rust Card

[vigith]

https://github.com/gojp/goreportcard has been archived. I am not sure what is the best to replace it; for now replacing it with

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.09%. Comparing base (128ddde) to head (6f9843e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3501   +/-   ##
=======================================
  Coverage   83.09%   83.09%           
=======================================
  Files         310      310           
  Lines       81395    81395           
=======================================
+ Hits        67632    67634    +2     
+ Misses      13168    13164    -4     
- Partials      595      597    +2     

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