gcc-13 cleaned up a few more transitive headers in it's STL: https://gcc.gnu.org/gcc-13/changes.html

As a result claws-mail-4.1.1 (and git) fails to build as:

claws-mail> In file included from html.h:12,
claws-mail>                  from iterators.cpp:1:
claws-mail> os_types.h:68:22: error: 'uintptr_t' in namespace 'std' does not name a type
claws-mail>    68 |         typedef std::uintptr_t                  uint_ptr;
claws-mail>       |                      ^~~~~~~~~
claws-mail> In file included from html.h:12,
claws-mail>                  from el_style.cpp:1:
claws-mail> os_types.h:68:22: error: 'uintptr_t' in namespace 'std' does not name a type
claws-mail>    68 |         typedef std::uintptr_t                  uint_ptr;
claws-mail>       |                      ^~~~~~~~~

The following seems to be enough to fix it, but I'm not sure it's the correct place to add missing header:

--- a/src/plugins/litehtml_viewer/litehtml/os_types.h
+++ b/src/plugins/litehtml_viewer/litehtml/os_types.h
@@ -1,6 +1,8 @@
 #ifndef LH_OS_TYPES_H
 #define LH_OS_TYPES_H

+#include <cstdint>
+
 namespace litehtml
 {
 #if defined( WIN32 ) || defined( _WIN32 ) || defined( WINCE )

Thanks!