Adding missing include.

include/rive/core/field_types/core_bytes_type.hpp

diff --git a/include/rive/core/field_types/core_bytes_type.hpp b/include/rive/core/field_types/core_bytes_type.hpp
index b0fb146..5e4a589 100644
--- a/include/rive/core/field_types/core_bytes_type.hpp
+++ b/include/rive/core/field_types/core_bytes_type.hpp
@@ -2,6 +2,7 @@
 #define _RIVE_CORE_BYTES_TYPE_HPP_
 
 #include <vector>
+#include <cstdint>
 
 namespace rive
 {