bump main to v6

Since podman main branch gets bumped to v6 we need to start building v6
images here as well.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Author: Luap99

podman-rpm-info-vars.sh

@@ -5,5 +5,5 @@
 # 2. Both PODMAN_VERSION and PODMAN_PR_NUM will have to be updated manually on release
 # PRs.
 # 3. If PODMAN_PR_NUM is empty, rpms will be fetched from the `rhcontainerbot/podman-next` copr.
-export PODMAN_VERSION="5.7.0-dev"
+export PODMAN_VERSION="6.0.0-dev"
 export PODMAN_PR_NUM=""