Bump Almalinux to 8.4

roles/netbootxyz/defaults/main.yml

@@ -101,6 +101,8 @@ releases:
     versions:
     - code_name: 8.3
       name: 8.3
+    - code_name: 8.4
+      name: 8.4
   alpinelinux:
     base_dir: alpine
     enabled: true