Rebuild for python 3.14

[stoiver]

Opt in to conda-forge's python314 migration so anuga ships CPython 3.14 packages.

Why now

The migration PR (#8) was closed back in March because the build genuinely failed:

meson-python: error: The package requires Python version <3.14,>3.8, running on 3.14.0rc3

That cap is gone. anuga upstream now declares requires-python = ">=3.10, <3.15" with a
Programming Language :: Python :: 3.14 classifier, and 3.3.8 already ships cp314 wheels on
PyPI for linux, macOS (x86_64 + arm64) and Windows. All runtime dependencies have py314 builds
(meshpy, pymetis, netcdf4, scipy, numpy, matplotlib-base), and the rest
(xarray, dill, utm, meson-python, pybind11) are noarch.

Because the bot only opens one PR per migration and #8 was closed, it never re-offered it — so
this opts in manually.

Changes

• add .ci_support/migrations/python314.yaml (copied verbatim from conda-forge-pinning)
• bump build number for the rebuild

Rerender to follow via @conda-forge-admin, please rerender.

Checklist

• Tests pass on all platforms for py3.10–3.14

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

[stoiver]

@conda-forge-admin, please rerender

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-webservice.

I tried to rerender for you, but it looks like there was nothing to do.

_{This message was generated by GitHub Actions workflow run https://github.com/conda-forge/conda-forge-webservices/actions/runs/29184512728. Examine the logs at this URL for more detail.}