Update polaris to 0.8.0-alpah.4

[xylar]

This version updates:

• mpas_tools to 1.3.0 -- brings in:
  • some improvements and fixes to build_jigsaw
  • a fix to write_netcdf() to handle a problem in the latest xarray (2025.8.0) when unlimited dimensions are sliced.
• jigsaw and jigsaw-python to 1.1.0

Checklist

• Testing comment in the PR documents testing used to verify the changes

[xylar]

Testing

I ran the pr suite and the cull tasks for all supported spherical meshes using this branch on Chrysalis. I don't expect bit-for-bit results compared with older JIGSAW so I didn't check that. But all tasks passed.