Remove `child_process` dependency for improved browser compatibility

⭐ Suggestion

Discussion #960

Currently, node-cron depends on child_process to execute string-based commands, which prevents it from being used in browser environments.

I propose completely removing the child_process dependency to enhance browser compatibility and make node-cron more versatile across different platforms.

Use Cases

Running node-cron in a browser-based environment.

❌ Related Problems

https://github.com/kelektiv/node-cron/issues/538 https://github.com/kelektiv/node-cron/issues/426 https://github.com/kelektiv/node-cron/issues/345 https://github.com/kelektiv/node-cron/issues/333 https://github.com/kelektiv/node-cron/issues/299 https://github.com/kelektiv/node-cron/issues/171