fix GCC 13 issues

GCC 13 removes `uint*_t` family of types from one of the common
includes so we need to explicitly include cstdint.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7224585f0421b729b8a6b703851f5a000ab2d900
diff --git a/msl_verify.hpp b/msl_verify.hpp
index 3f6983e..af0c2a2 100644
--- a/msl_verify.hpp
+++ b/msl_verify.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstdint>
 #include <string>
 
 namespace minimum_ship_level