The "update-contributors" step in CI/CD fails

We get the following output:

```
> karma-coverage@2.0.1 update-contributors
> grunt contributors

Running "npm-contributors" task
>> Cannot commit contributors changes:
>> Author identity unknown
>>
>> * Please tell me who you are.
>>
>> Run
>>
>> git config --global user.email "you@example.com"
>> git config --global user.name "Your Name"
>>
>> to set your account's default identity.
>> Omit --global to set the identity only in this repository.
>>
>> fatal: empty ident name (for ) not allowed
```

Corresponding to https://github.com/vojtajina/grunt-npm/blob/master/tasks/npm.js#L104-L106. It appears that although the grunt task shows as failed, the contributors update in package.json takes place because the changes are committed later by semantic-release-bot.