path resolution for git toplevel is wrong

[ptrebert]

probably a more general problem, but in the update workflow script, determining if and where the template-snakemake repository exists is logically flawed. What needs to be done here instead of just using Python's pathlib.Path.resolve is to determine the root of the repo (e.g. via calling git rev-parse --show-toplevel in the workflow directory) and then assume that the template repo is (or needs to be cloned) parallel to that.