Fixes build with GCC 13.

--- a/src/simd/Vector.hpp
+++ b/src/simd/Vector.hpp
@@ -23,6 +23,7 @@
 
 #include <type_traits>
 #include <cassert>
+#include <cstdint>
 
 // std::negation requires C++17, so defined own one
 template<typename B>