Update guide on using SLEAP on HPC

[niksirbi]

Description

What is this PR

• Bug fix
• Addition of a new feature
• Other

Why is this PR needed?

The guide was out of date because:

• I installed a new SLEAP module on HPC (corresponding to v1.3.4, and built against the new Ubuntu 24.04 cluster)
• SLEAP release v1.5 and updated links to docs

What does this PR do?

• Mentions the new module
• Warns about the fact that all currently installed SLEAP modules correspond to legacy (tensorflow) versions
• Updates all SLEAP links in the guide to point to legacy docs
• Adds nvidia-smi to example SLURM scripts (useful to have for debugging)
• Adds instructions on how to handle RGB-to-Grayscale conversion errors during inference (I keep encountering them on some videos)

References

neuroinformatics-unit/course-animals-in-motion#21
neuroinformatics-unit/movement#681

How has this PR been tested?

Local docs build.
I have tested the new SLEAP module by succesfully running training and inference on the CalMS21 data, on two types of GPU nodes: A4500 and RTX5000.

Considerations for review

I'd like to have this merged ahead of Thursday, Oct 9th, because I will point students to this guide as a useful resource.
I've also opened #76 to remind myself to install a new SLEAP>v1.5 module and update the guide accordingly at a future time.

Checklist:

• The code has been tested locally
• Tests have been added to cover all new functionality
• The documentation has been updated to reflect any changes
• The code has been formatted with pre-commit

[niksirbi]

Thanks @lochhh!