Remove shadow, because it comes from the community repo, which may be missing.

robertdebock · robertdebock · commit 1a0e001c9f22 · 2018-10-09T20:32:17.000+02:00
diff --git a/vars/main.yml b/vars/main.yml
@@ -48,7 +48,6 @@ bootstrap_stable_packages:
   Alpine:
     - ca-certificates
     - py-simplejson
-    - shadow
   CentOS-6:
     - libselinux-python
     - libsemanage-python
