feat: add support for Github Enterprise, fix #45

[eliamartani]

Description

Add support into config to retrieve custom Github url, allowing Github Enterprise to be used with this dependency.

This pull request was tested with two scenarios:

with repo

export default {
  baseUrl: "git.custom.com",
  baseUrlApi: "git.custom.com/api/v3",
  repo: "eliamartani/myrepo",
};

without repo

export default {
  baseUrl: "git.custom.com",
  baseUrlApi: "git.custom.com/api/v3",
};

Some other tests were added to cover some additions made with the Pull Request

Linked Issues

Closes #45

Additional context