fixes 512 compile reminders (#32582)

code/modules/reagents/chemistry/machinery/chem_master.dm

@@ -344,11 +344,16 @@
 		return null
 	else
 		var/md5 = md5(AM.name)
-#if DM_VERSION > 511
-#warn Refactor the loop in /obj/machinery/chem_master/adjust_item_drop_location() to make use of 512's list-like access to characters in a string
-#endif
 		for (var/i in 1 to 32)
+			#if DM_VERSION >= 513
+			#warning 512 is definitely stable now, remove the old code
+			#endif
+			
+			#if DM_VERSION >= 512
+			. += hex2num(md5[i])
+			#else
 			. += hex2num(copytext(md5,i,i+1))
+			#endif
 		. = . % 9
 		AM.pixel_x = ((.%3)*6)
 		AM.pixel_y = -8 + (round( . / 3)*8)