build: updated nlohmann to 3.11.2

[Jaskowicz1]

This PR updates nlohmann json to 3.11.2.

This was originally done in #982, but we've heard nothing back and we aren't 100% sure this works (our CIs do say this works, but a real test case is required for this as it's a huge change).

Code change checklist

• I have ensured that all methods and functions are fully documented using doxygen style comments.
• My code follows the coding style guide.
• I tested that my change works before raising the PR.
• I have ensured that I did not break any existing API calls.
• I have not built my pull request using AI, a static analysis tool or similar without any human oversight.

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[Jaskowicz1]

This PR is now marked as ready for review. It has been tested with my bot and works!