Makes 8x50 boxes have exactly 5 rounds more. (#3242)

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## About The Pull Request

Mystery PR.

## Why It's Good For The Game
Makes ammo for the illestren slightly cheaper! Enough for it to be as
good economically as pistols i think.
## Changelog

:cl:
balance: 8x50 boxes now come with 25 ammo as opposed to 20.
/:cl:

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code/modules/projectiles/boxes_magazines/ammo_boxes.dm

@@ -447,7 +447,7 @@
 	desc = "A box of standard 8x50mm ammo."
 	icon_state = "8x50mmbox"
 	ammo_type = /obj/item/ammo_casing/a8_50r
-	max_ammo = 20
+	max_ammo = 25
 
 /obj/item/ammo_box/ferropelletbox
 	name = "ammo box (ferromagnetic pellets)"