feat(model): enhance LoadFeed with timeout support and add tests

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"time"
 
 	"gitea.malaihome.work/ans/podcast-search-go/model"
 	"gitea.malaihome.work/ans/podcast-search-go/search"
@@ -24,7 +25,7 @@ func main() {
 	fmt.Printf("name: %s, feedUrl: %s\n", item.CollectionName, item.FeedURL)
 	feedUrl := "http://www.ximalaya.com/album/19206382.xml"
 
-	pod, err := model.LoadFeed(feedUrl)
+	pod, err := model.LoadFeed(feedUrl, 5*time.Second)
 	if err != nil {
 		panic(err)
 	}