Prisoners can no longer clock out of their sentence (#4329)

## About The Pull Request
Prisoners can no longer use the punch clock app on PDAs.
## Why It's Good For The Game
As silly as "John Ghoul, Prisoner has gone off-duty." is, we probably
shouldn't have prisoners clocking out.
## Proof Of Testing
<details>
<summary>Screenshots/Videos</summary>

<img width="490" height="308" alt="image"
src="https://github.com/user-attachments/assets/a45bd480-0dbc-4e15-bfe4-b70a68ed4003"
/>

<img width="505" height="320" alt="image"
src="https://github.com/user-attachments/assets/5f97d9f4-2fa2-4182-b74e-e34ee85f11b6"
/>

</details>

## Changelog
🆑
fix: fixed prisoners being able to clock out using the Plexagon Punch
Clock app
/🆑

---------

Co-authored-by: LT3 <83487515+lessthnthree@users.noreply.github.com>

modular_zubbers/modules/plexagon_selfserve/code/plexagon_selfserve.dm

@@ -74,6 +74,10 @@
 		if(tgui_alert(usr, "You are a member of security and/or command, make sure that you ahelp before punching out! If you decide to punch back in later, you will need to go to the Head of Personnel or Head of Security. Do you wish to continue?", "[src]", list("No", "Yes")) != "Yes")
 			return FALSE
 
+	if(istype(authenticated_card.trim, /datum/id_trim/job/prisoner))
+		tgui_alert(usr, "You cannot clock out of prison. Nice try, inmate.")
+		return TRUE
+
 	log_econ("[authenticated_card.registered_name] clocked out from role [authenticated_card.get_trim_assignment()]")
 	var/datum/component/off_duty_timer/timer_component = authenticated_card.AddComponent(/datum/component/off_duty_timer, TIMECLOCK_COOLDOWN)
 	if(important)