[tmux] Change prefix to M-\

This was conflicting with operations like manipulating dates in org-mode

home/modules/tmux/default.nix

@@ -23,12 +23,7 @@ in
   programs.tmux.historyLimit = 50000;
   programs.tmux.clock24 = true;
   programs.tmux.baseIndex = 1;
-  programs.tmux.prefix = "`";
+  programs.tmux.prefix = "M-\\\\";
-
-  programs.tmux.extraConfig = ''
-    bind -n S-Left previous-window
-    bind -n S-Right next-window
-  '';
 
   programs.tmux.plugins = with pkgs; [
     tmuxPlugins.cpu