fix: add missing includes in sidebarmodel.h/cpp for GCC build

Author: Milkii Brewster

src/library/sidebarmodel.cpp

@@ -8,6 +8,7 @@
 #include "moc_sidebarmodel.cpp"
 #include "util/assert.h"
 #include "util/cmdlineargs.h"
+#include "util/logger.h"
 
 namespace {
 

src/library/sidebarmodel.h

@@ -5,6 +5,8 @@
 #include <QModelIndex>
 #include <QVariant>
 
+#include "util/usersettings.h"
+
 class LibraryFeature;
 class QTimer;