Add support for Python 3.14 on windows builds

[zerocewl]

Add missing support for Python 3.14 on windows builds

closes #351

[zerocewl]

@samuelcolvin

I thought this is an easy one, but the first pipeline already fails with the windows cp3.13 builds

Built wheel for CPython 3.13 to dist\watchfiles-1.1.0-cp313-cp313-win_amd64.whl
   Compiling pyo3-build-config v0.25.1
   Compiling pyo3-ffi v0.25.1
   Compiling pyo3-macros-backend v0.25.1
   Compiling pyo3 v0.25.1
error: failed to run custom build command for `pyo3-ffi v0.25.1`

https://github.com/samuelcolvin/watchfiles/actions/runs/18474739835/job/52636624027

Because of the pyo3-ffi v0.25.1 error, i tried to simple bump pyo3 to 0.26.0, but the pipeline failed too. So feel free to close the pr if this is trash ;-)

[zerocewl]

@samuelcolvin

At least the last update commit seems to fix the pipeline. Not sure if the other updates should be reverted and taken in another pr?

fix taken from PyO3/maturin#2528

[samuelcolvin]

oh, nice chat.

I think we're not good, I've reverted some of the unnecessary things I tried to fix it, if this passes, I think we can make a new release.