repositories: distinguish between RHEL8 beta and GA

We need the same RPMs to work equally well on a host running a beta
release (pulling beta content) as on a machine running GA (pulling GA
content). Detect this at run-time and point at the right repository.

Testing this is a bit hairy as we are building 8.3 images, but obviously
there is currently no 8.3 content at the GA URLs.

Signed-off-by: Tom Gundersen <teg@jklm.no>

cmd/osbuild-image-tests/context-managers.go

@@ -115,7 +115,7 @@ func withBootedQemuImage(image string, ns netNS, f func() error) error {
 
 		var qemuCmd *exec.Cmd
 		if common.CurrentArch() == "x86_64" {
-			hostDistroName, err := distro.GetHostDistroName()
+			hostDistroName, _, err := distro.GetHostDistroName()
 			if err != nil {
 				return fmt.Errorf("cannot determing the current distro: %v", err)
 			}