Remove unused header in editor.

Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>

editor/add_metadata_dialog.cpp

@@ -30,6 +30,8 @@
 
 #include "add_metadata_dialog.h"
 
+#include "editor/themes/editor_scale.h"
+
 AddMetadataDialog::AddMetadataDialog() {
 	VBoxContainer *vbc = memnew(VBoxContainer);
 	add_child(vbc);