Remove deprecated coverage pkg

[LeonanCarvalho]

Recently I found that a previous change not related to workflows is failing in my other PR https://github.com/gofrs/uuid/pull/111

It is happening because the package golang.org/x/tools/cmd/cover is no longer active and marked as deprecated, that's why the workflow will fail.

Run go get golang.org/x/tools/cmd/cover
  go get golang.org/x/tools/cmd/cover
  shell: /usr/bin/bash -e {0}
  env:
    GO111MODULE: auto
    GOROOT: /opt/hostedtoolcache/go/1.19.4/x64
cannot find package "golang.org/x/tools/cmd/cover" in any of:
    /opt/hostedtoolcache/go/1.19.4/x64/src/golang.org/x/tools/cmd/cover (from $GOROOT)
    /home/runner/go/src/golang.org/x/tools/cmd/cover (from $GOPATH)
Error: Process completed with exit code 1.

The tests are focused on 1.18 e 1.19 and no longer needs to install golang.org/x/tools/cmd/cover

[codecov-commenter]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage :thumbsup:

Coverage data is based on head (8eba5cf) compared to base (9363593). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #115 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 4 4 Lines 448 448 ========================================= Hits 448 448 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=gofrs). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=gofrs)

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