update to Julia 1.9.4, add CUDA back into examples

[simonbyrne]

Purpose

Try to fix longruns

• updates to Julia 1.9.4
• initiatalizes CUDA inside examples project

To-do

Content

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• I have read and checked the items on the review checklist.

[szy21]

Trying longrun here: https://buildkite.com/clima/climaatmos-longruns/builds/1265

[simonbyrne]

Okay, so i figured out the problem:
https://buildkite.com/clima/climaatmos-longruns/builds/1268#018bf3a8-be9c-4070-abbd-e6dd2591b431/333-337

if you don't specify a CUDA runtime version, CUDA_Runtime_jll adds a cache dependency on the runtime library:
https://github.com/JuliaBinaryWrappers/CUDA_Runtime_jll.jl/blob/d7e700c623a51b93ef2421233f1dbc97d8de5904/.pkg/platform_augmentation.jl#L62-L82
which then gets invalidated if you run it on a different node.

The solution is to specify the CUDA version in the preferences.