do not pin MSBuild to VS2022; the windows-2025 image ships only VS2026

The windows-2025-vs2026 runner image has no VS2022 installation, so
selecting MSBuild 17 fails with "Unable to find MSBuild". VS2026 includes
the MSVC v143 build-tools component, so its MSBuild can build the
Projucer-generated v143 projects directly.