Unbind the C-z key

It’s rather dangerous under Sway, as i can’t restore a frame into running state after i press
it (although Emacs still happily responds).

configuration.org

@@ -3715,6 +3715,7 @@ With the new Transient package it will be easier.  I just don’t know how to us
  ("C-M-s" . isearch-forward)
  ("C-M-r" . isearch-backward)
  ("C-~" . toggle-char-case)
+ ("C-z" .  nil)
  :map ctl-x-map
  ("C-y" . gpolonkai/duplicate-line)
  ("_" . maximize-window)