fix: 修复peek方法的使用错误。

group.go

@@ -91,7 +91,7 @@ func (c *Group) MemberUIDs() []int64 {
 	var members []int64
 	c.PeekMembers(func(_ int64, s *session.Session) bool {
 		members = append(members, s.UID())
-		return false
+		return true
 	})
 	return members
 }