Core: Remove Player.h dependency from all the possible headers

src/server/scripts/Spells/spell_holiday.cpp

@@ -20,6 +20,7 @@
  * Scriptnames in this file should be prefixed with "spell_#holidayname_".
  */
 
+#include "Player.h"
 #include "ScriptMgr.h"
 #include "ScriptedCreature.h"
 #include "SpellScript.h"