Description of problem:
The workstation repos are not yet available for F31. That has been reported here, not yet acted upon:
https://pagure.io/fedora-workstation/issue/102

Also, DNF changed the default of skip_if_unavailable from True to False (a very bad move in my eyes):
https://fedoraproject.org/wiki/Changes/Set_skip_if_unavailable_default_to_false
That means that all repos that don't specify `skip_if_unavailable=False` in their metadata are considered mandatory, and all DNF operations immediately fail.

From the extra workstation repositories, pycharm and google-chrome already contain `skip_if_unavailable=True`. Steam and Nvidia don't contain anything (which means False now).

The consequence is that if a user enabled Steam or Nvidia repositories (which is quite visibly offered by GNOME Software on its front page), suddenly their system is non-operational. No new package can't be installed, no updates can't be installed or even are visible (even worse, GNOME Software claims the system is up to date). This affects both GNOME Software and DNF.

There are three ways to resolve this:
1. Make the repos accessible
2. Include `skip_if_unavailable=True` in their metadata
3. Push to revert the DNF defaults change

Please note that even if we make the repos accessible, I think it's very unwise to have them marked as mandatory. They are hosted by external parties (rpmfusion in this case), and any time the third party goes down, our package managers go down. And the users would be constantly required to toggle the repos on and off, based on their availability, just to get to proper Fedora content (this is one of the reasons why I believe the DNF change is a step in the wrong direction). Of course many users wouldn't even know what to do, it would be "just broken".

Therefore I strongly suggest to mark all the extra repos with `skip_if_unavailable=True` (or ask DNF team to reconsider).


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

How reproducible:
always

Steps to Reproduce:
1. run gnome-software
2. enable third party repos in the top banner
3. go to repositories menu and enable steam or nvidia repo
4. try to use gnome-software or DNF - gnome-software will stop displaying all content, DNF will immediately exit with error

Actual results:
The system is not easily usable when some of the extra workstation repos are enabled, but not accessible

Expected results:
The system stays easily usable when some of the extra workstation repos are enabled, but not accessible