Upgrade to Ubuntu 24.04 and Cuda 12.8.0

[badisa]

• Would have to upgrade to at least Cuda 12.5.1 to get Ubuntu 24.04 images, unless we want to build our own. With the release of the Nvidia RTX 50 series, upgrading to 12.8.0 seemed to make more sense
• A warning in the latest NVCC complains about how we handle our templating code. We have been inconsistent about this, but the practice seems to be to define the implementation of templated function in .cuh then declare the usage in .cu.

Example NVCC Error

/code/timemachine/timemachine/cpp/src/kernels/k_sampling.cuh(27): error #20281-D: in whole program compilation mode ("-rdc=false"), a global function template instantiation or specialization ("timemachine::k_setup_gumbel_max_trick_targeted_insertion ") will be required to have a definition in the current translation unit, when "-static-global-template-stub" will be set to "true" by default in the future. To resolve this issue, either use "-rdc=true", or explicitly set "-static-global-template-stub=false" (but see nvcc documentation about downsides of turning it off)