Revert "External Version bump for alpinelinux new version string "3.19""

This reverts commit 164e1e9a0902f6b66679cff24a41ec09796549f2.

roles/netbootxyz/defaults/main.yml

@@ -138,8 +138,8 @@ releases:
     mirror: http://dl-cdn.alpinelinux.org
     name: Alpine Linux
     versions:
-    - code_name: v3.19
-      name: '3.19'
+    - code_name: v3.18
+      name: '3.18'
     - code_name: edge
       name: Edge (development)
   anarchy: