fix: callbacks

Manually picked from https://github.com/Pocco81/auto-save.nvim/pull/67/,
namely 6203ae6d23625b93e563b8893cefb99e55ecb06f.

lua/auto-save/utils/data.lua

@@ -1,7 +1,5 @@
 local M = {}
 
-local cnf = require("auto-save.config").opts
-
 function M.set_of(list)
 	local set = {}
 	for i = 1, #list do
@@ -17,6 +15,8 @@ function M.not_in(var, arr)
 end
 
 function M.do_callback(callback_name)
+	local cnf = require("auto-save.config").opts
+
 	if type(cnf.callbacks[callback_name]) == "function" then
 		cnf.callbacks[callback_name]()
 	end