Fix regular expression

lua/sourcer/init.lua

@@ -22,7 +22,7 @@ function M.lookup()
 	local b = 1
 	local doi_links = {}
 	while true do
-		local x, y = response:find("/doi/[a-zA-Z]+/10.[0-9]+/[0-9.]+/gm", b, false)
+		local x, y = response:find("doi/[a-zA-Z]+/10.[0-9]+/[0-9.]+", b, false)
 
 		-- stop if no further occurrences are found
 		if x == nil or y == nil then