Description of problem:
When trying to add multiple GPG keys while adding a repo using dnf API, only the first GPG key is added.

EXAMPLE:
base.repos.add_new_repo('foo_repo', conf,
baseurl=['https://foo/bar'],
gpgkey=['https://foo/bar/key1','https://foo/bar/key2'],
gpgcheck=True)

Version-Release number of selected component (if applicable):

How reproducible:
Every time

Steps to Reproduce:
1.Add repo using API and add multiple GPG keys (see example above)
2.Only one GPG key is successfully added

Actual results:
Only one GPG key is added

Expected results:
Multiple GPG keys expected

Additional info:
Bug is already fixed upstream with this pull:
https://github.com/rpm-software-management/dnf/pull/1962