travis: Do pre-releases by default
travis: Do pre-releases by default

Switching it to a release is then done out-of-band (usually manually)

Signed-off-by: Fabian Deutsch <de69c509e52dfe544d526a81279fe21e1252748c@fedoraproject.org>

davidvossel/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,fabiand/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt,rmohr/kubevirt,rmohr/kubevirt,kubevirt/kubevirt,fabiand/kubevirt