Update CI dependency pins

[jl-wynen]

The pins where out of date with our minimum bounds in pyproject.toml which is breaking our docs build https://github.com/scipp/scippneutron/actions/runs/19627948536

[nvaytet]

Is the failing build a memory issue?

[jl-wynen]

Is the failing build a memory issue?

I don' think so. I get this on my laptop, too. But for 2_working-with-masks.ipynb, not 1_exploring-data.ipynb. But it is no where near my memory limit.

[jl-wynen]

I reduced Mantid to 6.13 due to #655

I also had to make some changes to a notebook because it still used the old .meta property. It didn't fail before because we use a year-old version of Scipp.