travis: run TEST-13-ENC-RAID-LVM on Fedora 29

Systemd in Fedora 30 is broken at the moment.
Fix: https://github.com/systemd/systemd/pull/12897

.travis.yml

@@ -18,7 +18,7 @@ env:
   - IMAGE=latest TESTS=04
   - IMAGE=latest TESTS=10
   - IMAGE=latest TESTS=11
-  - IMAGE=latest TESTS=13
+  - IMAGE=29 TESTS=13
   - IMAGE=29 TESTS=14
   - IMAGE=latest TESTS=15
   - IMAGE=latest TESTS=17