another typo

roles/nameserver/tasks/install_bind.yml

@@ -19,6 +19,6 @@
     path: "{{ named_conf_options }}"
     regexp: '^\s*listen-on \{.*\};'
     state: present
-    line: "\tlisten-on { {{ ansible_default-ipv4.address }}; };"
+    line: "\tlisten-on { {{ ansible_default_ipv4.address }}; };"
     insertafter: "options {"
     validate: "{{ named_checkconf }} %s"