move input into its own folder

input data is shared across multiple days' puzzles, so this is just neater. else i'd have to keep duplicating the input data lmao

01/main.lua

@@ -1,7 +1,7 @@
 input = {};
 
 -- import input from external file
-for line in io.lines("./input.txt") do
+for line in io.lines("../input/01.txt") do
   table.insert(input, line)
 end