Switch to line-length = 120

[Christian-B]

The official python recommendation is still 80.

ref: https://peps.python.org/pep-0008/#maximum-line-length

But if we are to follow that strictly then the docs and comments should be 72 max
No I do NOT suggest following the 72 limit

However based on https://gitlab.com/spinnaker2/SpiNNMan2/-/blob/main/pyproject.toml?ref_type=heads
SpiNNcloud are using 120

If we decide to adopt that future plan now ruff format https://docs.astral.sh/ruff/formatter/ will update the code to make use of that.

[rowleya]

Happy to have this, although even now with limited screen space on a laptop and various side-panels, more than 80 can mean some scrolling...