Change package version deletion criteria in docker.yaml

Signed-off-by: Timothy Rule <90191439+timrulebosch@users.noreply.github.com>

Author: timrulebosch

.github/workflows/docker.yaml

@@ -65,5 +65,5 @@ jobs:
         with:
           package-name: 'dse-${{ matrix.image }}'
           package-type: 'container'
-          min-versions-to-keep: 4
+          older-than: 7
           delete-only-untagged-versions: false