Pin Snakemake to <8

[victorlin]

Description of proposed changes

Version 8.0.0 was just released today. Pin to buy time to adjust for any breaking changes.

https://snakemake.readthedocs.io/en/stable/project_info/history.html#id2

Related issue(s)

Checklist

• [x] Checks pass

[corneliusroemer]

We wouldn't upgrade anyways as snakemake 8 has minimum python version 3.11 - and we pin python to 3.10 ;)

[victorlin]

Good point, we can see in the build summary that this doesn't change the Snakemake version. I'll merge it anyways though - this can't hurt in the short term!