add quotes around octal values

YAML loaders will load them as strings, providing a consistent behavior. This is also safer as JSON does not support octal values either.

roles/bastion/tasks/ssh.yml

@@ -4,6 +4,6 @@
   copy:
     src: "ssh/"
     dest: "~/.ssh/"
-    mode: 0600
+    mode: "0600"
     directory_mode: true
   become_user: "{{ main_user }}"