[gnote] Add missing include

[Aurimas Černius <aurimasc src gnome org>]

commit 45757dc77f5fca7866ee9f52e80707e28c1e069e
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Sun Apr 21 21:01:20 2019 +0300

    Add missing include

 src/itagmanager.hpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/src/itagmanager.hpp b/src/itagmanager.hpp
index 115908f6..51beac00 100644
--- a/src/itagmanager.hpp
+++ b/src/itagmanager.hpp
@@ -1,7 +1,7 @@
 /*
  * gnote
  *
- * Copyright (C) 2013,2017 Aurimas Cernius
+ * Copyright (C) 2013,2017,2019 Aurimas Cernius
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -20,6 +20,8 @@
 #ifndef _ITAGMANAGER_HPP_
 #define _ITAGMANAGER_HPP_
 
+#include <list>
+
 #include <glibmm/ustring.h>
 
 #include "tag.hpp"