Update reference to go cobertura package

- The previously referenced go cov cobertura report generating package
  in the docs is no longer maintained and has bugs in it that prevented
us from using it in our dogfooding of the test coverage visualization
feature for runner. Updated this link with the fork that has more recent
bug fixes and PRs.

doc/user/project/merge_requests/test_coverage_visualization.md

@@ -33,7 +33,7 @@ This format was originally developed for Java, but most coverage analysis framew
 for other languages have plugins to add support for it, like:
 
 - [simplecov-cobertura](https://rubygems.org/gems/simplecov-cobertura) (Ruby)
-- [gocover-cobertura](https://github.com/t-yuki/gocover-cobertura) (Golang)
+- [gocover-cobertura](https://github.com/boumenot/gocover-cobertura) (Golang)
 
 Other coverage analysis frameworks support the format out of the box, for example: