[pungi-fedora] PR #334: Use just F28 key since everything in rawhide is signed with F28 key now.

[Dennis Gilmore]

ausil merged a pull-request against the project: `pungi-fedora` that you are following.

Merged pull-request:

``
Use just F28 key since everything in rawhide is signed with F28 key now.
``

https://pagure.io/pungi-fedora/pull-request/334