Add #include <cstdint> for fixed-width integers

(cherry picked from commit e3cc7ee)

Author: i2z1

hilti/toolchain/include/ast/node-tag.h

@@ -3,6 +3,7 @@
 #pragma once
 
 #include <array>
+#include <cstdint>
 #include <string>
 
 namespace hilti::node {