ci/rpmostree: Bump to 2019.1

Should fix the issue that CI broke due to libsolv not being sync'd.

Closes: #1806
Approved by: jlebon

ci/rpmostree.sh

@@ -6,7 +6,7 @@ set -xeuo pipefail
 # Frozen to a tag for now to help predictability; it's
 # also useful to test building *older* versions since
 # that must work.
-RPMOSTREE_TAG=v2018.8
+RPMOSTREE_TAG=v2019.1
 
 dn=$(dirname $0)
 . ${dn}/libpaprci/libbuild.sh