Fix Slug Shot condition (#5556)

* Fixes #5555.
* Slug Shot should do less damage to monsters than players.
Thanks to @Balferian!

src/map/battle.cpp

@@ -4698,7 +4698,7 @@ static int battle_calc_attack_skill_ratio(struct Damage* wd, struct block_list *
 			skillratio += -100 + 1700 + 200 * skill_lv;
 			break;
 		case RL_SLUGSHOT:
-			if (target->type == BL_PC)
+			if (target->type == BL_MOB)
 				skillratio += -100 + 1200 * skill_lv;
 			else
 				skillratio += -100 + 2000 * skill_lv;