PoolBehavior does not add restarted process to pool.monitors

[fikomore]

Describe the bug
When child process of Pool process is restarted with call process.Exit("restart") (for the first time it is restarted as expected) it is deleted from pool.monitors but the new child is not added to pool.monitors so when process.Exit("restart") is called the child process is not restarted.

To Reproduce
Steps to reproduce the behavior:

1. Create a pool with eg. 1 worker
2. call process.Exit("restart") from child process
3. When process is restarted call process.Exit("restart") again
4. process is not restarted

Expected behavior
After each call process.Exit("restart") the process should be restarted

Environment (please complete the following information):

• Arch: x86_64
• OS: Linux
• Framework Version: 2.2.4

[fikomore]

This should fix the issue