Python 3.13+ can be built using Visual Studio 2026.
Explore if this improves performance.

Based on limited testing in #970 and with a physical Windows machine the following changes will likely be needed:

• VS 2026 must be installed in the Github action runner
  • This is not yet available in the GitHub provided runners, see Update/Add Visual Studio 2026 actions/runner-images#13291
  • Currently a depot-windows-2022-8 runner is used, 2025 will likely be needed, either depot or a GitHub runner.
• The call to the vcvars script in the workflow will need to use VS2026. On my test machine this is in ...\18\Community but this will depend on the install in the runner.
• --vs 2026 will need to be passed to the build.py command. This and the vcvars call will need to be conditional based on the Python version.

Related #919, #970, #933