fix: compilation failure with gcc >= 13

[VirtualTim]

Description of Change

It appears that gcc13 reordered some headers, so iostream no longer includes cstdint.
Files using cstdint via iostream need to be updated.
I've only changed one file, but there's sure to be more that need changing (see #2698).

Checklist

• Added description of change
• PR title follows semantic commit guidelines
• I acknowledge that all my contributions will be made under the project's license.

Notes: For testing - https://godbolt.org/z/6WWh3zs9G