fix: cleanup timers

[hayotbisonai]

What does this do?

This PR adds cleanup logic to handle existing timers in the selectExecJobsOutForRescheduling function of the scheduler. By stopping and clearing old timers, it prevents memory leaks and ensures that jobs are rescheduled correctly without accumulating unused timers.

Which issue(s) does this PR fix/relate to?

List any changes that modify/break current functionality

• Added cleanup logic to stop and clear existing timers before setting a new timer.
• Ensured that old timers are properly disposed of to avoid memory leaks.

Have you included tests for your changes?

Did you document any new/modified functionality?

• Updated example_test.go
• Updated README.md

Notes

• The changes focus on improving memory management by ensuring that previous timers are stopped and cleared.
• This update should help prevent potential memory leaks and ensure accurate job scheduling.

[JohnRoesler]

🧹 💯