Configure coverage threshold on commit status

[ybiquitous]

Which issue, if any, is this issue related to?

See #5891 (comment)

Is there anything in the PR that needs further explanation?

See https://docs.codecov.com/docs/commit-status

[ybiquitous]

Validation result:

$ cat codecov.yml | curl --data-binary @- https://codecov.io/validate
Valid!

{
  "comment": false,
  "coverage": {
    "status": {
      "project": {
        "default": {
          "threshold": 1.0
        }
      }
    }
  }
}

[jeddy3]

Thank you!