Fix the call function from the stdlib library on Python 3.9
Fix the call function from the stdlib library on Python 3.9

In short, we close a fd before the select.epoll.unregister(fd)
is called. The function originally ignored closed fd (EBADF) however
it's changed since Python 3.9+

Close the fd after it's unregistered.
See:
  - https://bugs.python.org/issue39239
  - https://github.com/python/cpython/commit/5b23f7618d434f3000bde482233c8642a6eb2c67

Thanks @shaded-enmity for the fix.

Fixes: #682

Co-authored-by: Pavel Odvody <3fcc220962e517bdd6ed0b04b536c843ef55a21b@redhat.com>

leapp-to/prototype,leapp-to/prototype,leapp-to/prototype,leapp-to/prototype