Adds missing MaxAPrate constant (#7169)

* Adds missing constant to script_constants.hpp.

src/map/script_constants.hpp

@@ -654,6 +654,7 @@
 	export_constant2("bCastrate",SP_CASTRATE);
 	export_constant2("bMaxHPrate",SP_MAXHPRATE);
 	export_constant2("bMaxSPrate",SP_MAXSPRATE);
+	export_constant2("bMaxAPrate", SP_MAXAPRATE);
 	export_constant2("bUseSPrate",SP_SPRATE);
 	export_constant2("bAddEle",SP_ADDELE);
 	export_constant2("bAddRace",SP_ADDRACE);