Remove the uncompressed tar artefact

The file may be useful locally, but for the other stages we don't need
it. Explicitly remove it since it tends to be 3-4x the size of
everything else.

v2
 - switch from rm to artefacts:exclude:

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

.gitlab-ci.yml

@@ -69,6 +69,8 @@ get_version:
   artifacts:
     paths:
       - output/*
+    exclude:
+      - output/*.tar
     expire_in: 2h
 
 rootfs: