refactor(app):移除测试代码中的授权令牌并调整更新检查逻辑

移除app_test.go中硬编码的GitHub授权令牌，避免安全风险。在app.go的CheckUpdate方法中，将授权令牌从请求头中移除，改为无认证方式获取版本信息，同时优化VIP用户下载链接逻辑。

app.go

@@ -239,7 +239,6 @@ func (a *App) CheckUpdate(flag int) {
 	releaseVersion := &models.GitHubReleaseVersion{}
 	_, err := resty.New().R().
 		SetResult(releaseVersion).
-		SetHeader("Authorization", "Bearer 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").
 		Get("https://api.github.com/repos/ArvinLovegood/go-stock/releases/latest")
 	if err != nil {
 		logger.SugaredLogger.Errorf("get github release version error:%s", err.Error())
@@ -250,7 +249,6 @@ func (a *App) CheckUpdate(flag int) {
 
 		tag := &models.Tag{}
 		_, err = resty.New().R().
-			SetHeader("Authorization", "Bearer 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").
 			SetResult(tag).
 			Get("https://api.github.com/repos/ArvinLovegood/go-stock/git/ref/tags/" + releaseVersion.TagName)
 		if err == nil {

app_test.go

@@ -54,7 +54,6 @@ func TestUpdateCheck(t *testing.T) {
 		SetResult(releaseVersion).
 		SetHeader("Accept", "application/vnd.github+json").
 		SetHeader("X-GitHub-Api-Version", "2022-11-28").
-		SetHeader("Authorization", "Bearer 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").
 		Get("https://api.github.com/repos/ArvinLovegood/go-stock/releases/latest")
 	//  https://api.github.com/repos/OWNER/REPO/releases/latest
 	if err != nil {