chore: Fix build w/ libstdc++13

```
In file included from cpp/src/util/logging.cpp:1:
cpp/src/util/logging.h:47:36: error: unknown type name 'uint8_t'
   47 | void output_hex (std::ostream &os, uint8_t const *data, size_t length);
```

Author: robinlinden

cpp/src/util/logging.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <array>
+#include <cstdint>
 #include <ostream>
 #include <vector>