replaced wrong variable operation

lua/sourcer/init.lua

@@ -2,8 +2,8 @@ local M = {}
 
 function M.lookup()
 	local keywords = vim.fn.getreg("*") -- receive yanked text
+	keywords = keywords:sub(2, #keywords)
 	local url = "https://dl.acm.org/action/doSearch?AllField=" .. keywords
-	url = url:sub(2, #url)
 	url, empty = url:gsub(" ", "+")
 
 	-- Setup a http socket and request