Fix Kitty window_id retrieval

The Kitty handler was failing to get the window_id and exiting with code
1,
causing dispatch to fallback to alternative handlers (jobstart,
terminal, etc).
This resulted in duplicate jobs.

In some environments additional (special) characters follow the window
ID.

Co-authored-by: Kelvin Stinghen <kelvin.stinghen@me.com>

Author: trekdemo

autoload/dispatch/kitty.vim

@@ -56,7 +56,7 @@ function! s:make(request) abort
 
   let cmd = s:kitty_launch_cmd(type, a:request, dispatch#prepare_start(a:request, cmd_with_capturing, 'make'))
   let output = system(cmd)
-  let window_id = matchstr(output, '^\d\+$')
+  let window_id = matchstr(output, '\d\+')
 
   if !empty(window_id)
     let s:waiting[window_id] = a:request