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

This reverts commit 2e258a68fd54bbff9524e8e2320b04a90bc2c66d.

roles/netbootxyz/defaults/main.yml

@@ -131,8 +131,8 @@ releases:
     mirror: http://dl-cdn.alpinelinux.org
     name: Alpine Linux
     versions:
-    - code_name: v
-      name: ''
+    - code_name: v3.15
+      name: '3.15'
     - code_name: edge
       name: Edge (development)
   anarchy: