Set ansible_python_interpreter to python3 on debian (fix error with mitogen) (#6633)

roles/bootstrap-os/tasks/bootstrap-debian.yml

@@ -86,6 +86,10 @@
   when:
     - need_bootstrap.rc != 0
 
+- name: Set the ansible_python_interpreter fact
+  set_fact:
+    ansible_python_interpreter: "/usr/bin/python3"
+
 # Workaround for https://github.com/ansible/ansible/issues/25543
 - name: Install dbus for the hostname module
   package: