fix(smartexit): use native OS methods to kill process trees; remove tree-kill dependency

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartexit',
-  version: '1.1.1',
+  version: '2.0.3',
   description: 'A library for managing graceful shutdowns of Node.js processes by handling cleanup operations, including terminating child processes.'
 }