bodhi-backend: Make sure zchunk dicts are installed

The zchunk dictionaries used to reduce the size of zchunk metadata seems to
not currently be installed on the bodhi server.  This patch makes sure they
are installed.

Signed-off-by: Jonathan Dieter <jdieter@gmail.com>

roles/bodhi2/backend/tasks/main.yml

@@ -18,6 +18,7 @@
   - bodhi-composer
   - python3-pyramid_sawing
   - sigul
+  - fedora-repo-zdicts
   # Are these still needed?
   - compose-utils
   - pungi-utils