Update NVIDIA CUDA signing key for CI; fix for building docs

[graemenail]

Description

See https://forums.developer.nvidia.com/t/notice-cuda-linux-repository-key-rotation/212772

Removes old signing key in favour of the updated one sso that CI works again

@snukky I'm not sure if you said this fix was in the coming sync or not, but I needed to fix it for CI on my fork anyway. Feel free to merge/close as needed

List of changes:

• Updated signing key for CUDA installs in CI

Added dependencies: none

How to test

Run CI

Checklist

• [x] I have tested the code manually
• [ ] I have run regression tests
• [x] I have read and followed CONTRIBUTING.md
• [ ] I have updated CHANGELOG.md

[graemenail]

Sigh. Docs are broken because of https://github.com/sphinx-doc/sphinx/issues/10291.